Light-emitting device and vehicle headlight

ABSTRACT

A light-emitting device includes a plurality of laser elements, a light-emitting section for emitting light in response to a laser beam, and an emission control section for controlling whether each of the plurality of laser elements emits light or not. At least a part of the plurality of laser elements is positioned in such a manner that irradiation regions of the light-emitting section are positioned at least partially differently.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/855,483, filed on Apr. 2, 2013, which claims priority to JapanesePatent Application No. 2012-087543, filed on Apr. 6, 2012, each of whichare hereby incorporated by reference in the present disclosure in itsentirety.

TECHNICAL FIELD

The present invention relates to a light-emitting device and a vehicleheadlight each having a high color rendering property and being capableof realizing any light distribution pattern.

BACKGROUND ART

In recent years, researches have been actively made into alight-emitting device which uses, as illumination light, fluorescencethat a light-emitting section containing a fluorescent body generates inresponse to excitation light emitted from an excitation light sourcewhich is a semiconductor light emitting element such as a light emittingdiode (LED) or a semiconductor laser (LD: Laser Diode).

A technique related to such a light-emitting device is exemplified bylight-emitting devices disclosed in Patent Literatures 1 through 4.

Patent Literature 1 allows a vehicle headlamp having variableillumination characteristics to be mechanically simply structured andimproves obstacle resistance and response speed. Patent Literature 2discloses a headlight which, while restraining an enlargement, iscapable of (i) reducing electric power consumption and (ii) formingdesired density in a light distribution pattern. Patent Literature 3discloses a vehicle lamp capable of electrically switching between ahorizontally wide light distribution pattern and a light distributionpattern suitable for AFS (Adaptive Front-lighting System) casting lightbeams leftward and rightward. Patent Literature 4 discloses a lightsource device which prevents a device from getting large-sized,increasing in weight, and getting high in manufacturing cost even in thelight source device equipped with a function of varying lightdistribution.

CITATION LIST

Patent Literatures

Patent Literature 1

Japanese Patent Application Publication, Tokukai, No. 2003-45210(Publication Date: Feb. 14, 2003)

Patent Literature 2

Japanese Patent Application Publication, Tokukai, No. 2011-157022 A(Publication Date: Aug. 18, 2011)

Patent Literature 3

Japanese Patent Application Publication, Tokukai, No. 2011-113668 A(Publication Date: Jun. 9, 2011)

Patent Literature 4

Japanese Patent Application Publication, Tokukai, No. 2011-134619 A(Publication Date: Jul. 7, 2011)

SUMMARY OF INVENTION Technical Problem

However, the techniques described in the above patent literatures have aproblem below.

That is, the vehicle headlamp of Patent Literature 1 etc. does not havea color rendering property which is sufficient to be used for a vehicleheadlamp. Furthermore, the vehicle headlamp of Patent Literature 1 etc.has difficulty in varying a light distribution pattern.

The present invention was made in view of the foregoing problem. Anobject of the present invention is to provide a light-emitting device, afloodlight, and a vehicle headlight each has a color rendering propertysufficient to be used for a vehicle headlamp and is capable of varying alight distribution pattern.

Solution to Problem

In order to solve the foregoing problem, a light-emitting device inaccordance with one aspect of the present invention is a light-emittingdevice, including: a plurality of laser beam sources each for emitting alaser beam; a light-emitting section for emitting light in response tothe laser beam emitted from at least one of the plurality of laser beamsources; and emission control means for controlling whether each of theplurality of laser beam sources emits light or not, at least a part ofthe plurality of laser beam sources being positioned in such a mannerthat irradiation regions of the light-emitting section which arerespectively irradiated with the laser beams emitted from the pluralityof laser beam sources are positioned at least partially differently.

Advantageous Effects of Invention

The light-emitting device of the present invention has a color renderingproperty sufficient to be used for a vehicle headlamp, and is capable ofvarying a light distribution pattern.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1

FIG. 1 is a view schematically illustrating an example of a headlamp inaccordance with the present embodiment.

FIG. 2

FIG. 2 is a view schematically illustrating a relation between aplurality of laser elements and a light-emitting section in alight-emitting device in accordance with the present embodiment.

FIG. 3

FIG. 3 is a view illustrating an example of an operation of thelight-emitting device.

FIG. 4

FIG. 4 is a view illustrating another example of an operation of thelight-emitting device.

FIG. 5

FIG. 5 is a view illustrating still another example of an operation ofthe light-emitting device.

FIG. 6

Each of (a) and (b) of FIG. 6 illustrates an example of a positionalrelationship among a plurality of irradiation regions formed on alight-emitting section.

FIG. 7

FIG. 7 is a view schematically illustrating a paraboloid of revolutionof a parabolic mirror.

FIG. 8

(a) of FIG. 8 is a top view of a parabolic mirror. (b) of FIG. 8 is anelevation view of the parabolic mirror. (c) of FIG. 8 is a side view ofthe parabolic mirror.

FIG. 9

FIG. 9 is a block diagram illustrating an example of a control sectionincluded in the headlamp in accordance with the present embodiment.

FIG. 10

FIG. 10 is a flowchart showing an example of a flow of a process carriedout by the headlamp in accordance with the present embodiment.

FIG. 11

(a) of FIG. 11 is a view illustrating an example of a range offloodlighting in a case where a vehicle including the headlamp inaccordance with the present embodiment passes an oncoming vehicle. (b)of FIG. 11 is a view illustrating an example of a range of floodlightingin a case where the vehicle including the headlamp in accordance withthe present embodiment detects an animal (risk factor) in front of thevehicle.

FIG. 12

(a) of FIG. 12 is a view illustrating a light distribution pattern ofthe headlamp in accordance with the present embodiment in a case where avehicle is driven in a nation where a driver is required by law to driveon the right side. (b) of FIG. 12 is a view illustrating a lightdistribution pattern of the headlamp in accordance with the presentembodiment in a case where a vehicle is driven in a nation where adriver is required by law to drive on the left side.

FIG. 13

(a) of FIG. 13 is a view illustrating an example of a range offloodlighting formed by light emitted from the headlamp. (b) of FIG. 13is a view illustrating an example of an irradiation region formed on alight-emitting section in a case where the range of floodlightingillustrated in (a) of FIG. 13 is formed.

FIG. 14

FIG. 14 is a view showing a flow of a process carried out by theheadlamp.

FIG. 15

Each of (a) through (c) of FIG. 15 illustrates an example of arelationship between a tilt angle of a vehicle and change of anirradiation region.

FIG. 16

FIG. 16 is a view schematically illustrating how illumination lightemitted from a vehicle has an influence on an oncoming vehicle at astart of an uphill slope.

FIG. 17

FIG. 17 is a schematic view illustrating a modification example of theheadlamp in accordance with the present embodiment.

FIG. 18

FIG. 18 is a schematic view illustrating another modification example ofthe headlamp in accordance with the present embodiment.

FIG. 19

FIG. 19 is a schematic view illustrating still another modificationexample of the headlamp in accordance with the present embodiment.

FIG. 20

Each of (a) and (b) of FIG. 20 is a view schematically illustrating anexample of a configuration in the vicinity of a laser element arrayincluded in the headlamp illustrated in FIG. 19. (c) of FIG. 20 is aview schematically illustrating an example of a configuration of onelaser chip and one laser element array.

FIG. 21

Each of (a) and (b) of FIG. 21 is a view illustrating other example ofthe configuration in the vicinity of the laser element array included inthe headlamp illustrated in FIG. 19.

FIG. 22

FIG. 22 is a schematic view illustrating still another modificationexample of the headlamp in accordance with the present embodiment.

DESCRIPTION OF EMBODIMENTS

With reference to drawings, the following description will discuss alight-emitting device 1 etc. in accordance with the present embodiment.Hereinafter, the same parts and the same members are given the samereference signs, and have the same names and the same functions.Accordingly, detailed explanations thereof are not repeated.

[Outline of Operation of Light-Emitting Device 1]

Initially, a description will be made below as to an outline of anoperation of the light-emitting device 1 with reference to FIG. 2 etc.,and then as to a specific configuration of a headlamp. Thelight-emitting device 1 in accordance with the present embodiment has abasic structure constituted by a plurality of laser elements 2, alight-emitting section 3, and an emission control section 4 (emissioncontrol means) (see FIG. 1). The light-emitting device 1 is included ineach of headlamps 100-500 mentioned later.

FIG. 2 is a view schematically illustrating a relation between theplurality of laser elements 2 and the light-emitting section 3. In FIG.2, the number of the laser elements 2 is twelve. However, the number isnot limited to twelve. As illustrated in FIG. 2, in the light-emittingdevice 1, under control of the emission control section 4, the pluralityof laser elements 2 provided in a matrix manner emit laser beams. Thelight-emitting section 3 emits fluorescence in response to the laserbeams.

As illustrated in FIG. 2, the plurality of laser elements 2 are providedin a matrix manner with respect to the light-emitting section 3.Furthermore, light control sections (e.g. collimating lenses 30 inlater-mentioned Modification Example 2 (see FIG. 18)) are positioned insuch a manner as to correspond to the laser elements 2, respectively.Consequently, laser beams respectively emitted from the laser elements 2are radiated to the whole of the light-receiving surface of thelight-emitting section 3 in a matrix manner so that irradiation regionson the light-receiving surface do not overlap each other. Consequently,it is possible to cause a fluorescent body of the light-emitting section3 to efficiently emit light, and control of emission of the laserelements 2 allows changing a range of floodlighting of illuminationlight in accordance with light distribution characteristics.Furthermore, it is possible to cause the light-emitting section 3 touniformly emit light.

FIGS. 3-5 illustrate Operation Examples of the light-emitting device 1.In FIGS. 3-5, for simplification, it is assumed that a parabolic mirror5 (light-casting section) (see FIG. 1) is used for the light-emittingdevice 1, and the light-emitting section 3 is provided at substantiallya focal position (first focal position) of the parabolic mirror 5.

In the light-emitting device 1, the emission control section 4(mentioned later) determines whether each of the laser elements 2 isdriven or not to control whether each of the laser elements 2 emitslight or not, thereby changing areas irradiated with laser beams andpositions irradiated with the laser beams on the light-emitting section3. A range of floodlighting of light which has been emitted from thelight-emitting section 3 and is reflected by the parabolic mirror 5 canbe changed depending on a change in areas irradiated with laser beams orpositions irradiated with the laser beams.

As illustrated in FIG. 3, when the emission control section 4 causes allof the laser elements 2 to emit laser beams, a range of floodlighting a1with the maximum area is formed. In this case, irradiation regionsformed on the light-receiving surface of the light-emitting section 3are formed on all segments of the light-receiving surface, respectively.

FIG. 4 illustrates a range of floodlighting a1 formed when only a partof the plurality of laser elements 2 emits a laser beam. In FIG. 4, anirradiation region is formed to include only a part of thelight-receiving surface of the light-emitting section 3 which partcorresponds to a part of the laser elements 2 selected as a target to bedriven by the emission control section 4 (e.g. only one segment of thelight-receiving surface). The range of floodlighting a1 formed byillumination light emitted from the irradiation region is more limitedin FIG. 4 than in FIG. 3.

FIG. 5 illustrates a range of floodlighting a1 formed when a part of theplurality of laser elements 2 emits a laser beam. Unlike FIG. 4, in FIG.5, the emission control section 4 controls whether each of the pluralityof laser elements 2 emits a laser beam or not so that only one segmentof the light-receiving surface (region A in FIG. 5) is not irradiatedwith the laser beam. In this case, the range of floodlighting a1 isformed in such a manner as to exclude a range a2 corresponding to theregion A.

As described above, the light-emitting device 1 is designed such thatthe plurality of laser elements 2 are positioned in such a manner thatirradiation regions of the light-emitting section 3 are positioned atleast partially differently and each of the plurality of laser elements2 are controlled to emit a laser beam or not, thereby freely changing alight distribution pattern of illumination light. Furthermore, use ofthe laser elements 2 enables the light-emitting device 1 to securesufficient luminance, and inclusion of the light-emitting section 3 foremitting light in response to the laser beam enables the light-emittingdevice 1 to have improved color rendering property and higher contrastof light whose wavelength is other than that of the laser beam.

As described above, the light-emitting device 1 can emit light to only apredetermined position, and therefore can illuminate a necessary portionand does not illuminate an unnecessary portion. Therefore, thelight-emitting device 1 can reduce power consumption of alater-mentioned headlamp.

[Schematic Structure of Headlamp]

With reference to FIG. 1, the following description will discuss anexample of a schematic structure of a headlamp 100 (light-emittingdevice, vehicle headlight) in accordance with the present embodiment.FIG. 1 is a view schematically illustrating an example of the headlamp100 in accordance with the present embodiment.

As illustrated in FIG. 1, the headlamp 100 includes the laser elements2, the light-emitting section 3, the emission control section 4, aparabolic mirror 5 (light-casting section), initial mirrors 6 (lightcontrol section, mirror), a heat radiating base 7 (heat radiatingsection), fins 8 (heat radiating section), a light-emitting sectionsupporter 9, and a wavelength cut coating 10.

The headlamp 100 can generate illumination light from a laser beamemitted from the laser element 2, and control light distributioncharacteristics and light intensity distribution of the illuminationlight.

The headlamp 100 may be provided in plural at both ends of a front of anautomobile (including motor cycle etc.) on which the headlamp 100 ismounted. For convenience, a description will be made below as to a casewhere one headlamp 100 is used for lighting.

(Laser Element 2)

The laser element 2 is a light-emitting element which functions as anexcitation light source that emits a laser beam. The laser element 2 mayhave one light-emitting point for each chip or have a plurality oflight-emitting points for each chip.

Use of a laser beam as excitation light allows efficiently exciting afluorescent body contained in the later-mentioned light-emitting section3 so as to emit light with higher luminance than a conventional lightsource, and further allows downsizing the light-emitting section 3. Inthe present embodiment, a laser beam emitted from one laser element 2forms, on the light-emitting section 3 via the initial mirror 6, anirradiation region of 100 μm to 1000 μm in diameter (i.e. spot size ofexcitation light is 100 μm to 1000 μm in diameter).

The headlamp 100 illustrated in FIG. 1 includes the plurality of laserelements 2, and each of the plurality of laser elements 2 emits a laserbeam as excitation light. Since the laser element 2 is a high luminancelight source, it can efficiently narrow an irradiation region on thelight-receiving surface of the light-emitting section 3. This allowscasting light with a narrow distribution angle.

In the present embodiment, the number of the laser elements 2 istwenty-four. That is, laser beams respectively emitted from the laserelements 2 form twenty-four irradiation regions on the light-receivingsurface. The light-receiving surface is a surface of the light-emittingsection 3 which surface receives laser beams. The laser elements 2 arepositioned on the heat radiating base 7 in such a manner that thetwenty-four irradiation regions are formed uniformly (in a 8×3 matrixmanner) on the light-receiving surface. This allows exciting thefluorescent body of the light-emitting section 3 in a matrix manner bythe laser beams emitted from the plurality of laser elements 2. Thenumber of the laser elements 2 is not limited to twenty-four and may beany number as long as the number can realize radiation of the laserbeams to the whole of the light-receiving surface of the light-emittingsection 3.

The wavelength of the laser beam from the laser element 2 is 395 nm(blue-violet) or 450 nm (blue) for example. However, the wavelength isnot limited to them, and may be selected suitably according to the kindof the fluorescent body contained in the light-emitting section 3.

The laser element 2 is mounted on a metal package of 5.6 mm in diameter,and emits a laser beam with an output of 2 W and a wavelength of 395 nm(blue violet, 380-415 nm). The laser element 2 is connected with a wire,and receives a power etc. via the wire.

The wavelength is not limited to 395 nm, and may be selected suitablyaccording to the fluorescent body used in the light-emitting section 3.

In FIG. 1, the plurality of laser elements 2 are positioned uniformly onthe heat radiating base 7. However, the present invention is not limitedto this configuration, and a distance between adjacent laser elements 2may be determined individually.

(Heat Radiating Base 7)

The heat radiating base 7, which is a supporting member for supportingthe plurality of laser elements 2, is made of metal (e.g., aluminum orcopper). Therefore, the heat radiating base 7 is highly thermallyconductive and can efficiently radiate heat generated in the pluralityof laser elements 2 provided thereon.

Note that a member supporting the laser element 2 may be a membercontaining a highly thermally conductive substance (e.g., siliconcarbide or aluminum nitride) other than metal. However, it is morepreferable that the member supporting the laser element 2 be made of,for example, highly thermally conductive metal.

(Fin 8)

The fin 8, which is provided on the heat radiating base 7, functions asa cooling section (heat radiating mechanism) which cools heattransferred from the laser element 2 to the heat radiating base 7. Thefin 8, which has a plurality of heat radiating plates, enhances heatradiating efficiency by increasing an area of a contact part withatmosphere.

In the present embodiment, the heat radiating base 7 and the fins 8 areintegrally molded by aluminum die casting, and the laser elements 2 areprovided on them via Si paste (insulating thermal-conductive resin).

Note that the fin 8 does not necessarily need to abut on the heatradiating base 7 and that a heat pipe, a water-cooled pipe, a Peltierdevice, or the like may be provided between the heat radiating base 7and the fin 8. It is only necessary that the cooling section which coolsthe heat radiating base 7 have a cooling function (heat radiatingfunction). The cooling section which cools the heat radiating base 7 ina water-cooling mode may perform cooling by use of a radiator.Alternatively, the cooling section may perform forced cooling by use of,for example, a fan.

(Initial Mirror 6)

The initial mirrors 6 are positioned between the plurality of laserelements 2 and the light-emitting section 3, and control guide of laserbeams from the plurality of laser elements 2 to the light-emittingsection 3. In other words, the initial mirrors 6 reflect laser beamsfrom the plurality of laser elements 2, respectively, therebycontrolling guide of the laser beams.

Specifically, laser beams emitted from the plurality of laser elements 2respectively are reflected by the initial mirrors 6 to be substantiallycollimated beams with a narrower width in a longitudinal direction, andthen guided to the light-emitting section 3 via a window of theparabolic mirror 5.

This configuration allows the plurality of laser elements 2 to bepositioned freely with respect to the light-emitting section 3.

(Structure of Initial Mirror 6)

In the present embodiment, the initial mirror 6 is an off-axis parabolicmirror whose focal point is substantially equal to a light-emittingpoint of the laser element 2. The initial mirror 6 converts a laser beamfrom the laser element 2 into a collimated beam and controls a lightpath of the collimated beam. It is more preferable that the initialmirror 6 is an aspheric mirror capable of correcting an astigmaticdifference of the laser element 2 (laser chip) and converting a laserbeam into a collimated beam. This configuration can further improve acollimating property. Alternatively, the initial mirror 6 may be otherparabolic mirror.

Since the plurality of laser elements 2 are provided on the heatradiating base 7, the plurality of initial mirrors 6 are provided insuch a manner as to correspond to the laser elements 2 respectively soas to face light-emitting points of the laser elements 2 respectively.

(Function of Initial Mirror 6)

As described above, the initial mirror 6 in accordance with the presentembodiment converts a diverging beam (laser beam emitted from the laserelement 2) into a collimated beam. Furthermore, use of the initialmirror 6 allows downsizing the window of the parabolic mirror 5.

A light path of a laser beam from the laser element 2 to thelight-emitting section 3 illustrated in FIG. 1 is consideredspecifically. The widths of three laser beams (in lateral direction onpaper) emitted from the laser elements 2 depend on the distance betweenthe laser elements 2. However, the widths of the three laser beamshaving been reflected by the initial mirror 6 are reduced (inlongitudinal direction on paper). This allows downsizing the window ofthe parabolic mirror 5, realizing effective use of light emitted fromthe light-emitting section 3.

Since the headlamp 100 is a light source for a vehicle headlamp, theheadlamp 100 is required to have a laterally long light distributionfinally as illustrated in FIG. 13. Therefore, the initial mirror 6reflects a laser beam from the laser element 2 in such a manner that thelaser beam is compressed in a longitudinal direction to have a laterallylonger shape on the light-emitting section 3.

As described above, the initial mirror 6 in accordance with the presentembodiment has two functions of collimating a diverging beam andcompressing the beam in a longitudinal direction.

FIG. 1 illustrates a configuration including the initial mirrors 6.Alternatively, the function similar to the initial mirror 6 can berealized by using a collimating lens and a plane mirror. Alternatively,in a case where a collimating lens or a collimating mirror is providedinside the laser element 2 to enable the laser element 2 to emit acollimated beam, the function similar to the initial mirror 6 can berealized by using a plane mirror.

Furthermore, use of the initial mirror 6 in controlling guide of a laserbeam allows reducing deterioration in a coating film than use of thecollimating lens 30. Therefore, use of the initial mirror 6 is desirablein consideration of securing long-term reliability.

(Material of Initial Mirror 6)

The initial mirror 6 is obtained by coating AlN ceramics which is asubstrate with (i) Al which is a reflective film and (ii) aluminum oxidewhich is an antioxidant film. However, the present invention is notlimited to this.

Desirable examples of the substrate are materials with small thermalexpansion coefficient, such as glasses (e.g. BK7, silica glass),polycarbonate, acrylic, FRP, SiC, and Al₂O₃. In a case where ultimatecollimating accuracy is not required so exactly, metals such as Al maybe used.

The reflective film is desirably a metal such as Ag and Pt. Thereflective film may be a film having a multilayered structure, such asSiO₂/TiO₂ multilayered film.

The antioxidant film may be made of silicon oxide etc. The antioxidantfilm is not necessarily coated.

The initial mirror 6 may be provided with an enhanced reflective film(enhanced reflection structure, such as HR coated film) on its surface.This configuration allows reducing reflection loss (mirror loss) of alaser beam due to the initial mirror 6.

(Description on Irradiation Region)

That is, at least a part of the plurality of laser elements 2 may bepositioned in such a manner that irradiation regions of thelight-emitting section 3 which are respectively irradiated with thelaser beams emitted from the plurality of laser elements 2 arepositioned at least partially differently.

That is, as illustrated in (a) of FIG. 6, the plurality of laserelements 2 may be positioned in such a manner that all irradiationregions which are respectively irradiated with laser beams from thelaser elements 2 are positioned differently or, as illustrated in (b) ofFIG. 6, the plurality of laser elements 2 may be positioned in such amanner that at least a part of each of the irradiation regions isoverlapped with each other and other part of each of the irradiationregions is positioned differently. Furthermore, although notillustrated, the plurality of laser elements 2 may be positioned in sucha manner that some of the plurality of irradiation regions are partiallyoverlapped with each other and others of the plurality of irradiationregions are positioned wholly differently.

It is desirable when an irradiation region formed by a laser beamemitted from one laser element 2 is required to have higher luminance onthe light-emitting section, the irradiation region has a smaller area.

In FIG. 6, for convenience, the number of irradiation regions, i.e. thenumber of laser elements 2 which has formed the irradiation regions,respectively, is smaller than the number of laser elements 2 in FIG. 1.

(Light-Emitting Section 3)

The light-emitting section 3 emits fluorescence in response to a laserbeam emitted from the laser element 2. That is, the light-emittingsection 3 emits light in response to a laser beam emitted from at leastone of the plurality of laser elements 2.

The light-emitting section 3 contains a fluorescent body (fluorescentsubstance) which emits fluorescence by absorbing a laser beam.

For example, the light-emitting section 3 is a light-emitting bodycontaining a fluorescent body, such as a light-emitting body havingparticles of a fluorescent body dispersed inside a sealant (sealedtype), a light-emitting body obtained by solidifying particles of afluorescent body, or a light-emitting body obtained by applying(depositing) particles of a fluorescent body onto a substrate made of ahighly thermally conductive material (thin-film type). In the presentembodiment, the light-emitting section 3 is formed by applying powder ofa fluorescent body on a tilt section 9 a of the light-emitting sectionsupporter 9 using TiO₂ as a binder in such a manner as to be arectangular thin film of 4 mm×2 mm with a thickness of 0.1 mm.

The light-emitting section 3 is positioned by the light-emitting sectionsupporter 9 in such a manner as to be close to the focal point of theparabolic mirror 5. Therefore, fluorescence emitted from thelight-emitting section 3 is reflected by a reflection curved surface ofthe parabolic mirror 5, so that an optical path of the fluorescence iscontrolled.

As illustrated in FIG. 1, the light-emitting section 3 is preferablysmaller than the parabolic mirror 5 (e.g. approximately one-tenth of theparabolic mirror 5). In this case, it is possible to efficiently castlight from the light-emitting section 3 ahead of the parabolic mirror 5.

Furthermore, the light-emitting section 3 is desirably larger thanirradiation regions (laser beam irradiation range) irradiated with laserbeams emitted from all the laser elements 2.

(Tilt Positioning of Light-Emitting Section 3)

The light-emitting section 3 is positioned at a tilt on the tilt section9 a of the light-emitting section supporter 9 in such a manner as toenable fluorescence from the light-emitting section 3 to be efficientlyreflected by the parabolic mirror 5 and is cast by the parabolic mirror5. The tilt section 9 a is tilted by approximately 15° in an incidentdirection of a laser beam with respect to a plane perpendicular to theincident direction. Light emitted from the light-emitting section 3 hasa substantially lambertian distribution. Accordingly, if the tiltsection 9 a is formed in such a manner that a laser-beam-irradiationplane of the tilt section 9 a is perpendicular to the incident directionof the laser beam, a region with the highest luminous intensity out oflight emitted from the light-emitting section 3 is positioned at thewindow of the parabolic mirror 5, resulting in lower floodlightingefficiency.

In consideration of the floodlighting efficiency, it is desirable thatthe laser-beam-irradiation plane is tilted by approximately 15°. If thefloodlighting efficiency is not taken into consideration, the tiltsection 9 a may be formed in such a manner that thelaser-beam-irradiation plane of the tilt section 9 a is perpendicular tothe incident direction of the laser beam.

In a case where the window of the parabolic mirror 5 is designed to havea structure capable of transmitting a laser beam and reflecting lightemitted from the light-emitting section 3, even if the tilt section 9 ais formed in such a manner that the laser-beam-irradiation plane of thetilt section 9 a is perpendicular to the incident direction of the laserbeam, the floodlighting efficiency would be improved, althoughproduction costs increase.

(Fluorescent Body)

The present embodiment uses BAM (BaMgAl₁₀O₁₇:Eu), BSON (Ba₃Si₆O₁₂N₂:Eu),or Eu-α (Ca-α-SiAlON:Eu) as the fluorescent body of the light-emittingsection 3 so that the fluorescent body emits white fluorescence inresponse to laser beams which have been generated by the respectivelaser elements 2 and each have a wavelength of 395 nm. The fluorescentbody of the light-emitting section 3 is, however, not limited to theabove, and may be so selected as appropriate that the headlamp 100 foran automobile emits white illumination light having a chromaticitywithin a predetermined range stipulated in the related law(s).

For example, it is possible to use another oxynitride fluorescent body(e.g., a sialon fluorescent body such as JEM (LaAl(SiAl)₆N₉O: Ce) orβ-SiAlON), a nitride fluorescent body (e.g., a CASN (CaAlSiN₃:Eu)fluorescent body), a SCASN ((Sr,Ca) AlSiN₃:Eu) fluorescent body), anApataite ((Ca,Sr)₅(PO₄)₃Cl:Eu), or a III-V group compound semiconductornanoparticle fluorescent body (e.g., indium phosphide:InP).

Alternatively, white light can be obtained by incorporating a yellowfluorescent body (or green and red fluorescent bodies) into thelight-emitting section 3 and irradiating the light-emitting section 3with a laser beam of 450 nm (blue) (or so-called near-blue laser beamwhose peak wavelength is in a range of not less than 440 nm and not morethan 490 nm).

(Sealed Type)

A sealing material of which the light-emitting section 3 of a sealedtype is made is, for example, a resin material such as a glass material(e.g., inorganic glass or organic/inorganic hybrid glass) or a siliconeresin. Low-melting glass may also be used as the glass material. Thesealing material is preferably highly transparent, and is preferablyhighly heat-resistant in a case where a laser beam is high in output.The light-emitting section 3 may be sealed with, for example, siliconoxide or titanium oxide by a sol-gel process.

The light-emitting section 3 may have, on a top surface thereof, ananti-reflection structure which prevents reflection of a laser beam. Inthe case of a sealed-type light-emitting body, since it is easy tocontrol a shape of the top surface of the light-emitting section 3, itis particularly desirable to form an anti-reflection film.

(Thin-Film Type)

In a case where the light-emitting section 3 is a thin-film typelight-emitting body, Al, Cu, AlN ceramic, SiC ceramic, aluminum oxide,Si, or the like is used as a substrate. Fluorescent body particles areapplied to or deposited on the substrate, and then the substrate isdivided into substrates each having a desired size. Thereafter, thesubstrates are fixed to the light-emitting section supporter 9 by use ofa highly thermally conductive adhesive.

In a case where Al or Cu, for example, is used as the substrate, it isdesirable that a side of the substrate on which side no fluorescent bodyparticles are deposited (a side of the substrate which side faces thelight-emitting section supporter 9) be coated with TiN, Ti, TaN, Ta, orthe like as a barrier metal. Further, the barrier metal may be coatedwith Pt or Au, for example.

It is desirable to use, as a highly thermally conductive adhesive,eutectic solder of SnAgCu, AuSn, or the like. However, the highlythermally conductive adhesive is not limited to those.

(Spot Size of Excitation Light)

In the present embodiment, an irradiation region (spot size ofexcitation light) on the light-emitting section 3 has a diameter of100-1000 μm. The reason is as follows.

1) Minimum Size

In order to emit white light, a plurality of fluorescent bodies are usedin the light-emitting section 3. The grain size of each fluorescent bodyis approximately 10 μm. When three kinds of fluorescent bodies are usedin the light-emitting section 3 for emitting white light uniformly, evenif the three kinds of fluorescent bodies are blended in ratios of 1:1:1,the size of an irradiation region is required to be of 20 μm indiameter. In reality, since the blend of the fluorescent bodies ischanged according to a necessary color temperature, the size of anirradiation region required to emit white light is of approximately 50μm in diameter. Furthermore, use of the fluorescent bodies without anytreatment may generate, depending on a range of floodlighting, a colordistribution corresponding to distributions of individual fluorescentparticles. Therefore, it is desirable that the laser beam is radiated sothat the size of the irradiation region is of 100 μm or more indiameter.

2) Maximum Size

This is a value determined according to a range of floodlighting whichone laser element 2 is capable of forming.

(Size of Irradiation Region in Case of Using Blue Laser Element)

In a case of using the laser element 2 which emits a near-blue laserbeam (blue laser element), since a laser beam is cast, it is necessaryto set an output of the laser beam to be class 1 of IEC60825-1.

In a case where the laser element 2 mixes a blue laser beam with ablue-violet laser beam (in a case where the laser element 2 includes ablue laser element and a blue-violet laser element), it is desirable inconsideration of a light emission efficiency that regions of individualfluorescent bodies in the light-emitting section 3 are positioneddifferently according to irradiation regions of individual laser beams.For example, a YAG fluorescent body is used for an irradiation region ofa blue laser beam, and BAM, BSON, and Eu-α are used for an irradiationregion of a blue-violet laser beam (i.e. these fluorescent bodies areapplied separately).

In this case, it is desirable in terms of safety that the size of anirradiation region irradiated with a blue laser beam emitted from oneblue laser element is equal to or larger than the size of an irradiationregion irradiated with a blue-violet laser beam emitted from oneblue-violet laser element.

If the light emission efficiency is not taken into consideration,individual fluorescent bodies may be blended and applied on the wholesurface of the light-emitting section 3 instead of being appliedseparately (e.g. blend of YAG fluorescent body and BAM, BSON, and Eu-α).

(Emission of Light Other than White Light)

Light emitted from the light-emitting section 3 is not limited to whitelight. The light-emitting section 3 may emit light having chromaticitydefined in a light-emitting device.

In a case where the laser element 2 includes an infrared emission laserelement serving as an infrared camera light source, the light-emittingsection 3 also serves as a scatterer for casting an infrared laser beamto a desired region.

(Light-Emitting Section Supporter 9)

The light-emitting section supporter 9 made of a highlythermal-conductive metal etc. supports the light-emitting section 3 atthe tilt section 9 a which is one end of the light-emitting sectionsupporter 9, and is connected with the parabolic mirror 5 so that thelight-emitting section 3 is substantially at a focal position of theparabolic mirror 5.

In the present embodiment, the light-emitting section supporter 9 ismade of Al. Alternatively, the light-emitting section supporter 9 may bemade of highly thermo-conductive ceramics such as AlN and SiC.

In the present embodiment, a fluorescent body is applied on thelight-emitting section supporter 9 using titanium oxide as a binder,thereby fixing the light-emitting section 3. The binder also may besilicon oxide etc.

In a case where the light-emitting section 3 is a thin film, it isdesirable that a plane of the light-emitting section supporter 9 whichplane faces the light-emitting section 3 is coated with TiN, Ti, TaN, Taetc. serving as a barrier metal. Furthermore, the barrier metal may becoated with Pt, Au etc.

The other end of the light-emitting section supporter 9 may beconnected, via the parabolic mirror 5, to a heat radiating member (notillustrated) which is highly thermally conductive. Therefore, heat ofthe light-emitting section 3 which heat is generated by a laser beam istransmitted to each of the light-emitting section supporter and the heatradiating member, so that the heat is radiated efficiently.

(Parabolic Mirror 5)

The parabolic mirror 5 reflects and controls light emitted from thelight-emitting section 3. Furthermore, the parabolic mirror 5 castslight to a light distribution area (light-castable range) which is arange in which the headlamp 100 (device including the parabolic mirror5) can cast light. That is, the range of floodlighting a1 (see FIG. 3)is formed by illumination light which is emitted from the light-emittingsection 3 in response to laser beams from the plurality of laserelements 2.

The parabolic mirror 5 casts illumination light emitted from thelight-emitting section 3.

The parabolic mirror 5 reflects fluorescence emitted by thelight-emitting section 3, and casts the reflected fluorescence to thelight distribution area. The parabolic mirror 5 forms a light flux(illumination light) which travels in a predetermined solid angle.Accordingly, it is unnecessary to provide the headlamp 100 with a convexlens 11. That is, unlike a headlamp 200 of Modification Example 1including an elliptic mirror 20 and the convex lens 11, the headlamp 100controls light from the light-emitting section 3 to be substantiallycollimated light and casts the substantially collimated light only byusing the parabolic mirror 5.

The parabolic mirror 5 may be a member on which a metal thin film isformed or may be a metal member.

FIG. 7 is a conceptual diagram illustrating a paraboloid of revolutionof the parabolic mirror 5. As illustrated in FIG. 7, the parabolicmirror 5 includes, in a reflection plane thereof, at least a part of apartial curved surface that is obtained by cutting, along a planecontaining a rotation axis which is a symmetry axis of a parabola, acurved surface (parabolic curved surface) formed by causing the parabolato rotate around the rotation axis.

A part of the parabolic mirror 5 thus shaped is provided so as to face atop surface of the light-emitting section 3, the top surface beinglarger in area than a side surface of the light-emitting section 3.Namely, the parabolic mirror 5 is provided so as to cover the topsurface of the light-emitting section 3 (so as to face an illuminated(light-receiving) surface that is a surface of the light-emittingsection 3 to which surface a laser beam is emitted). From anotherviewpoint, at least a part of the parabolic mirror 5 is provided at aradiation angle at which light that is emitted from light-emittingsection 3 has the highest luminous intensity when seen from thelight-emitting section 3.

In a case where the light-emitting section 3 and the parabolic mirror 5are provided in a positional relationship as described above, it ispossible to efficiently cast fluorescence of the light-emitting section3 in a given solid angle. This allows fluorescence to be used withhigher efficiency.

(Half Parabolic Mirror)

The parabolic mirror 5 may be a half parabolic mirror or the like(described below) provided that the parabolic mirror 5 has a parabolicshape. The parabolic mirror 5 may also be an off-axis parabolic mirroror a multi-facet type parabolic mirror.

(a) of FIG. 8 is a top view of the parabolic mirror 5, (b) of FIG. 8 isan elevation view of the parabolic mirror 5, and (c) of FIG. 8 is a sideview of the parabolic mirror 5. (a) to (c) of FIG. 8 show examples ineach of which for simple illustration of an explanatory view, theparabolic mirror 5 has been formed by hollowing a member which is arectangular parallelepiped.

In each of (a) of FIG. 8 and (c) of FIG. 8, a curved line indicated by asign 5 a shows a parabolic curved surface. In a case where the parabolicmirror 5 is seen from the front, an opening 5 b (exit via whichillumination light outgoes) thereof is semicircular (see (b) of FIG. 8).

(Window of Parabolic Mirror 5)

The parabolic mirror 5 has a window (not illustrated) via which a laserbeam is transmitted or passes. The window may be a penetrating hole ormay include a transparent member capable of transmitting a laser beam.For example, the window may be a transparent plate having a filter whichtransmits a laser beam and reflects white light (fluorescence fromlight-emitting section 3). This configuration allows preventing lightemitted from the light-emitting section 3 from leaking out of thewindow.

The parabolic mirror 5 is an optical member suitable for convertinglight from near-focal point of the mirror into substantially collimatedlight. On the other hand, the parabolic mirror 5 exhibits greataberration with respect to light far from the focal point. Consequently,light far from the focal point is cast as a larger spot than light nearthe focal point even if they have the same luminance. Use of thisphenomenon allows irradiating a range far from the light-casting axis(in case of vehicle headlamp, a close range in a side direction withrespect to a travelling direction (e.g. range of floodlighting a3 in (b)of FIG. 11)) with a large spot.

In a case where such a property is not required, a spherical mirror, amulti-facet mirror etc. may be used. The light-casting section does notnecessarily employ the parabolic mirror 5, and may select a suitablemirror according to the purpose of the light-emitting device. Forexample, the light-casting section may employ an elliptic mirror 20illustrated in FIG. 17 or may employ a multi-facet mirror capable ofgenerating any light distribution, a free-form surface mirror, a multimirror etc.

(Substantially Parallel Light)

Substantially parallel light does not need to be completely parallel andmay have an angle of floodlighting (a vertex angle at which a luminousintensity is halved) of 20° or less.

The present embodiment sets angles of floodlighting for respectiveelements constituting the laser elements 2. From the viewpoint oflight-distribution control, the elements constituting the laser elements2 are set to have respective angles of floodlighting each falling withina range of 0.1° to 20°. Particularly in a case of a vehicle headlamp, itis desirable to set the angle of floodlighting of each of the pluralityof laser elements 2 which emit light in a vehicle-traveling direction(in a range of ±8° with respect to an axis of a vehicle) to be not morethan 3° in order to realize a finer light distribution.

(Wavelength Cut Coating 10)

The wavelength cut coating 10 blocks light within a particularwavelength range. In the present embodiment, the wavelength cut coating10 cuts light of 400 nm or less in wavelength, and blocks a laser beamof 395 nm in wavelength.

This provides a user with a device that is friendly to the human eye.What wavelengths to block may be selected as appropriate by selecting adesired kind of the wavelength cut coating 10. Further, the wavelengthcut coating 10 may be replaced with a wavelength cut filter.

(Emission Control Section 4)

The emission control section 4 controls whether each of the plurality oflaser elements 2 emits a laser beam or not. Furthermore, the emissioncontrol section 4 may control output of a laser beam from each of theplurality of laser elements 2. The emission control section 4 will bedetailed later.

[Other Configuration of Headlamp 100]

With reference to FIG. 9, the following description will discuss otherconfiguration of the headlamp 100 etc. in accordance with the presentembodiment. FIG. 9 is a block diagram mainly illustrating an example ofa control section 12 included in the headlamp 100. As illustrated inFIG. 9, the headlamp 100 includes the control section 12 and a camera 16in addition to the aforementioned configuration.

(Camera 16)

The camera 16 continuously captures images of an area including alight-distribution area ahead of the vehicle. The camera 16 ispositioned, for example, in a vicinity of a rearview mirror providedforward of a room of the vehicle. The camera 16 may be a moving imagecapturing device used to capture a moving image at a television framerate.

The camera 16 starts capturing an image upon radiation of a laser beamfrom the laser element 2, and outputs a captured motion image to thecontrol section 12. The control section 12 can detect and identify apredetermined object by analyzing the motion image, and can generate arange of floodlighting a1 according to the result of the identification.

The camera 16 may be a camera for visible light, a camera for infraredlight, or a camera for both visible light and infrared light. Designingthe camera 16 to be for infrared light facilitates sensing homothermalanimals including a human being.

The technique for identifying the kind of an object in a moving imagecaptured by the camera 16 is not limited to the above, and may be apublicly known technique.

(Tilt Detection Section 15)

A tilt detection section 15 detects the tilt of a vehicle as a whole,particularly the tilt of a vehicle with respect to a horizontal plane.The tilt detection section 15 finds a tilt angle of a vehicle, andoutputs an angle signal to the emission control section 4. The tiltdetection section 15 detects the tilt of a vehicle by a publicly knownmethod described in Japanese Patent Application Publication No.2011-37337, Japanese Patent Application Publication No. 2009-204459,Japanese Patent Application Publication No. 2009-184463, Japanese PatentApplication Publication No. 2005-283290 etc. The detection method is notparticularly limited as long as the method can quickly respond to apositional change in vehicle.

(Control Section 12)

The control section 12 controls members constituting the headlamp 100 byexecuting a control program for example. The control section 12 mainlyincludes an object detection section 13 (detection means), an objectidentification section 14 (identification means), the tilt detectionsection 15, and the emission control section 4. The control section 12carries out various processes by reading out a program stored in astorage section (not illustrated) in the headlamp 100 to, for example, aprimary storage section (not illustrated) constituted by a RAM (RandomAccess Memory) etc. and executing the program according to necessity.The storage section 12 may be an external device connected with thelight-emitting device 1 and the headlamp 100.

(Object Detection Section 13)

The object detection section 13 analyzes a motion image captured by thecamera 16 so as to detect an object in the motion image. Specifically,the object detection section 13 acquires a motion image from the camera16 and detects an object in a light distribution area of the motionimage.

When the object detection section 13 detects an object in the lightdistribution area of the motion image, the motion detection section 13outputs, to the object identification section 14, a detection signalindicative of coordinates at which the object is detected.

The camera 16 may be replaced with an infrared radiation radar thatradiates an infrared ray to an object present in a light-distributionarea and senses a reflected wave from that object. Alternatively, thecamera 16 may be used in combination with such an infrared radiationradar. The case involving an infrared radiation radar can, similarly tothe case involving the camera 16, also use a widely usable technique tosense an object present in a light-distribution area.

(Object Identification Section 14)

The object identification section 14 identifies, by image recognition,the kind of an object at coordinates indicated by the detection signaloutputted from the object detection section 13. Specifically, the objectidentification section 14, upon obtaining a detection signal from theobject detection section 13, extracts features (for example, movingspeed, shape, and position) of the object indicated by the detectionsignal, and thus calculates a feature value, which is a numericalrepresentation of the features.

Then, the object identification section 14 refers to a reference valuetable that manages reference values each of which is a numericalrepresentation of the features of the kind of object, and retrieves,from the reference value table, a reference value having a differencefrom the calculated feature value which difference is within apredetermined threshold.

The reference value table manages, for example, respective referencevalues corresponding to a vehicle, a road sign, a pedestrian, an animal,and an expected obstacle and the like. The object identification section14, in the case where it has identified a reference value having adifference from the calculated feature value which difference is withinthe predetermined threshold, determines that the object represented bythat reference value is the object detected by the object detectionsection 13.

When the object identification section 14 determines that the objectdetected by the object detection section 13 is an object registered inthe reference value table in advance, the object identification section14 outputs, to the emission control section 4, an identification signalindicative of the object and coordinates at which the object isdetected.

(Emission Control Section 4)

The emission control section 4 controls whether a laser element 2corresponding to a detection region including the detected object emitslight or not in accordance with the kind and position of the objectindicated by the identification signal transmitted from the objectidentification section 14.

Specifically, in a case where the kind of an object indicated by theidentification signal outputted from the object identification section14 is an oncoming vehicle, a vehicle in front etc., the emission controlsection 4 controls a laser element 2 corresponding to a detection regionwhere the oncoming vehicle, the vehicle in front etc. are detected insuch a manner that the amount of casting light to a light distributionarea corresponding to the detection region is in a level which a driverof the oncoming vehicle, the vehicle in front etc. does not feelglaring. That is, the emission control section 4 controls the laserelement 2 in such a manner that the laser element 2 does not emit alaser beam or the laser element 2 emits a laser beam in a lower outputlevel.

On the other hand, in a case where the kind of an object indicated bythe identification signal outputted from the objection identificationsection 14 is a traffic sign, an obstacle etc., the emission controlsection 4 increases output of the laser element 2 which allows castinglight to a light distribution area corresponding to a detection regionwhere the traffic signal, the obstacle etc. are detected.

Furthermore, in accordance with the angle signal transmitted from thetilt detection section 15, the emission control section 4 controls thelaser element 2 corresponding to a range of floodlighting a1corresponding to the angle of a vehicle body indicated by the anglesignal so that the laser element 2 emits or not.

Furthermore, even when the emission control section 4 does not receivethe identification signal or the angle signal, the emission controlsection 4 controls each of the plurality of laser elements 2 whether toemit a laser beam or not in accordance with a desired light distributionpattern such as light distribution characteristics of a passingheadlamp.

The following description will discuss Operation Examples 1-4 of theheadlamp 100. It should be noted that Operation Examples 1-4 are merelyexamples and how the headlamp 100 operates is not limited to theseexamples.

Specific Operational Example 1

First, the following description deals with an example of how theemission control section 4 operates in accordance with an objectdetected by the object detection section 13, with reference to FIGS. 10and 11. FIG. 10 is a view showing an example of a flow of a processcarried out by the headlamp 100 in accordance with the presentoperational example. FIG. 11 is a schematic view illustrating an exampleof a range of floodlighting formed by the process carried out by theheadlamp 100.

First, the camera 16 (i) captures a moving image of a light distributionarea in front of a vehicle at an angle of view at which an image infront of the vehicle can be captured (S1), and (ii) transmits the movingimage thus captured to the object detection section 13 (see FIG. 10).

Next, the object detection section 13 analyzes the moving image capturedby the camera 16, so as to detect an object in the light distributionarea (S2). In a case where the object detection section 13 detects anobject in the light distribution area in the moving image, the objectdetection section 13 transmits, to the object identification section 14,a detection signal indicating coordinates at which the object has beendetected.

Then, in a case where the object identification section 14 obtains thekind of the object at coordinates indicated by the detection signalreceived from the object detection section 13, the object identificationsection 14 identifies the kind of the object at the coordinatesindicated by the detection signal (S3). That is, on receipt of thedetection signal from the object detection section 13, the objectidentification section 14 works out a feature value by (i) extractingfeatures of the object at the coordinates indicated by the detectionsignal, e.g., a moving speed of the object, a shape of the object, and aposition of the object, and (ii) digitalizing the features thusextracted.

Then, the object identification section 14 refers to a reference table,so as to search such a reference value that a difference between thereference value and the feature value thus calculated is within apredetermined threshold. In a case where such a reference value that adifference between the reference value and the feature value thuscalculated is within the predetermined threshold is found, the objectidentification section 14 determines that an object indicated by thereference value is identical with the object detected by the objectdetection section 13.

On the basis of a result of determination described above, the objectidentification section 14 supplies, to the emission control section 4,an identification signal indicating (i) the kind of the object indicatedby the reference value and (ii) a detection region where the object hasbeen detected. For example, in a case where the object identificationsection 14 identifies the kind of the object thus detected as anoncoming vehicle, as illustrated in (a) of FIG. 11, the objectidentification section 14 transmits, to the emission control section 4,an identification signal indicating a detection region corresponding toa region where the oncoming vehicle has been detected.

Next, on the basis of coordinate values indicated by the identificationsignal received from the object identification section 14, the emissioncontrol section 4 controls whether each of the plurality of the laserelements 2 emits a laser beam or not, so as to control whether to castlight from the light-emitting section 3 toward the object. That is, onthe basis of the identification signal, the emission control section 4controls whether each of the plurality of laser elements 2 emits a laserbeam or not, so as to change an area or a position of each ofirradiation regions formed on the light-emitting section 3 by the laserbeam (S4).

For example, in the case of (a) of FIG. 11, the emission control section4 controls the plurality of laser elements 2 so that (i) one(s) of theplurality of laser elements 2 does not emit a laser beam, which one(s)of the plurality of laser elements 2 is arranged in a positioncorresponding to a position indicated by the coordinate values in themoving image, at which the oncoming car has been detected in the movingimage, and (ii) the other ones of the plurality of laser elements 2 emita laser beam. This makes it possible to cast light from thelight-emitting section 3 toward, among a normal range of floodlightingL, a range of floodlighting a1 excluding a range of floodlighting a2 inwhich the object is included, as illustrated in (a) of FIG. 11.Accordingly, it is possible to reduce unpleasant brightness or dazzlegiven to a driver of an oncoming vehicle or a driver of a vehicle infront, for example. It is therefore possible to realize a safe andcomfortable traffic environment.

Further, in the case of (b) of FIG. 11, the emission control section 4controls the plurality of laser elements 2 so that one(s) of theplurality of laser elements 2 emits a laser beam, which one(s) of theplurality of laser elements 2 is arranged in a position corresponding toa position indicated by the coordinate values in the moving image, atwhich a deer (an accident factor) has been detected, and (ii) the otherones of the plurality of laser elements 2 do not emit a laser beam.Alternatively, the emission control section 4 (i) increases an output(s)of the one(s) of the plurality of laser elements 2, arranged in theposition corresponding to the position indicated by the coordinatevalues of the accident factor, to be higher than those of the other onesof the plurality of laser elements 2, or (ii) decreases outputs of theother ones of the plurality of laser elements 2 to be lower than that ofthe one(s) of the plurality of laser elements 2, arranged in theposition corresponding to the position indicated by the coordinatevalues of the accident factor. This makes it possible to cause, in thenormal range of floodlighting L (the range of floodlighting a1), a rangeof floodlighting a3, in which the deer is included, to be brighter thanthe other range of the normal range of floodlighting L. That is, itbecomes possible to illuminate, with brighter light, the deer which isan accident factor.

In this way, in the headlamp 100, the emission control section 4controls whether each of the plurality of laser elements 2 emits a laserbeam or not, so that cast light (i) includes an object (e.g., a roadsign, a pedestrian, an animal, an obstacle, etc.) detected by the objectdetection section 13 or (ii) does not include an object (e.g., anoncoming vehicle, a vehicle in front, etc.) detected by the objectdetection section 13.

With the arrangement, in a case where the object detected by the objectdetection section 13 is a road sign, a pedestrian, or an animal, forexample, such an object can be illuminated with brighter light. That is,it becomes possible for a driver to read a road sign or identify apedestrian or an obstacle, by viewing such an object with bright light.Accordingly, it is possible to realize a safe driving environment.

Meanwhile, in a case where the object detected by the object detectionsection 13 is a vehicle or the like, floodlighting can be controlled sothat such an object is not included in the range of floodlighting a1. Itis therefore possible to prevent a driver of an oncoming vehicle or thelike from being given unpleasant glare, for example.

That is, the identification of the kind of an object, carried out by theobject identification section 14, makes it possible to (i) controloptimally whether each of the plurality of laser elements 2 emits alaser beam or not in accordance with the kind of the object andtherefore (ii) adjust the range of floodlighting a1 in accordance withthe kind of the object.

Specific Operational Example 2

Each of (a) and (b) of FIG. 12 illustrates an operational example of howa light distribution pattern of a vehicle is adjusted in accordance withtraffic regulations of a nation in which the vehicle is driven. (a) ofFIG. 12 is a view illustrating a light distribution pattern of theheadlamp 100 of a vehicle, in a case where the vehicle is driven in anation where a driver is required by law to drive on the right side. (b)of FIG. 12 is a view illustrating a light distribution pattern of theheadlamp 100 of a vehicle, in a case where the vehicle is driven in anation where a driver is required by law to drive on the left side.

For example, in a case where a driver drives a vehicle in France where adriver is required by law to drive on the right side, it is necessary toadjust a light distribution pattern in accordance with a pattern for thedriving on the right side. On the other hand, in a case where a driverdrives in England where a driver is required by law to drive on the leftside, it is necessary to adjust the light distribution pattern inaccordance with a pattern for the driving on the left side. The emissioncontrol section 4 changes a position of each of irradiation regions of alaser beam on the light-emitting section 3 so as to satisfy the lightdistribution pattern of illumination light, ruled in the nation where adriver is required by law to drive on the right side, or the lightdistribution pattern of illumination light, ruled in the nation where adriver is required by law to drive on the left side.

Specifically, in a case where a driver comes and goes with his/hervehicle between England and France, for example, whether each of theplurality of laser elements 2 emits a laser beam or not is controlled inconjunction with the GPS so as to form the range of floodlighting a1which is in conformity with a corresponding nation's law. In this way,the headlamp 100 of the present invention can be applied to a vehicleused in any nation in the world, and can be used on the vehicle.

Specific Operational Example 3

Further, the emission control section 4 controls, in accordance withdriver's selection of a headlight for driving or a headlight for passingeach other, whether each of the plurality of laser elements 2 emits alaser beam or not, so that the light distribution range is (i) in arange satisfying a light distribution property standard of a headlightfor driving, ruled under a corresponding nation's law, or (ii) in arange satisfying a light distribution property standard of a headlightfor passing each other, ruled under a corresponding nation's law. Thismakes it possible to form the range of floodlighting a1 in accordancewith such a light distribution property standard.

The following description deals with how a range of floodlightingsatisfying a light distribution property standard of a headlight forpassing each other is formed, with reference to FIG. 13. (a) of FIG. 13is a view illustrating an example of a range of floodlighting formed bylight emitted from the headlamp 100. (b) of FIG. 13 is a viewillustrating an example of an irradiation region formed on thelight-emitting section 3 in a case where the range of floodlightingillustrated in (a) of FIG. 13 is formed.

Unlike the headlight for driving, the headlight for passing each otherrequires significantly-delicate light distribution control, so as torealize the light distribution property of the headlight for passingeach other. Since the headlamp 100 has an arrangement in which theplurality of laser elements 2 are arranged in a matrix manner (see FIGS.1 and 2, for example), the emission control section 4 can realize thelight distribution property of the headlight for passing each other bycontrolling whether each of the plurality of laser elements 2 emits alaser beam or not.

(a) of FIG. 13 illustrates a case where the emission control section 4carries out the aforementioned control and therefore a range offloodlighting a4 is formed. That is, the emission control section 4controls the plurality of laser elements 2 so that light is not casttoward a range a5 in a range of floodlighting having the largest area(the range of floodlighting a1 in FIG. 3), which range of floodlightingis formed in a case where all the plurality of laser elements 2 emit alaser beam. With the control, it is possible to prevent illuminationlight from being emitted toward, particularly, an oncoming lane (see (a)of FIG. 13).

In this case, an irradiation region A2 corresponding to the range offloodlighting a4 and a non-irradiation region A1 corresponding to therange a5 are formed in accordance with the control of whether each ofthe plurality of laser elements 2 emits light or not (see (b) of FIG.13).

Here, segments on a light-receiving surface of the light-emittingsection 3 illustrated in (b) of FIG. 13 correspond to respectiveirradiation regions formed by a laser beam emitted from the plurality oflaser elements 2. In (b) of FIG. 13, a segment in the vicinity of thecenter of the light-emitting section 3 is smaller in size than a segmentwhich is not in the vicinity of the center of the light-emitting section3. That is, the plurality of laser elements 2 are arranged so that laserelements 2 corresponding to segments provided in the vicinity of thecenter of the light-emitting section 3 are densely provided.

With the arrangement, the headlamp 100 can realize, in the vicinity ofthe center of the headlamp 100, formation of a range of floodlightingwhich is more similar to the light distribution property of theheadlight for passing each other, for which significantly-delicate lightdistribution control is required.

Specific Operational Example 4

Next, the following description deals with, with reference to FIGS. 14through 16, a case where, in accordance with a tilt angle of a vehicledetected by the tilt detection section 15, the emission control section4 controls whether each of the plurality of laser elements 2 emits alaser beam or not, so as to change an irradiation region. FIG. 14 is aview showing a flow of a process carried out by the headlamp 100 of thepresent operational example. Each of (a) through (c) of FIG. 15illustrates an example of a relationship between a tilt angle of avehicle and change of an irradiation region. FIG. 16 is a viewschematically illustrating how illumination light emitted from a vehiclehas an influence on an oncoming vehicle at a start of an uphill slope.

Generally, in a case where a vehicle 110 passes an oncoming vehicle 111at a start of an uphill slope, the vehicle 110 gives a driver of theoncoming vehicle 111, for example, unpleasant glare of illuminationlight 110L emitted from the vehicle 110, as illustrated in FIG. 16.Further, in a conventional vehicle, changing a range of floodlighting ofillumination light in accordance with tilt of the conventional vehiclerequires moving a reflector itself of a headlamp of the conventionalvehicle. Such movement requires a large moving mechanism, and a speed ofmoving the reflector is slow. Accordingly, in a case where such a movingmechanism is employed to change a range of floodlighting in a verticaldirection (longitudinal direction), (i) there is a high risk that adriver of an oncoming vehicle might be given unpleasant glare, andtherefore (ii) it is difficult to secure traffic safety. For the reasonsdescribed above, the moving mechanism is mainly used to change a rangeof floodlighting in a horizontal direction (right-and-left direction),in which a slow moving speed of the mechanism does not causes a bigproblem.

Meanwhile, the emission control section 4 of the headlamp 100 controls,in accordance with a result of detection by the tilt detection section15 (tilt of the vehicle with respect to a horizontal plane), whethereach of the plurality of laser elements 2 emits a laser beam or not, soas to change a position of the irradiation region. This makes itpossible to (i) adjust the position of the range of floodlighting a1 inaccordance with the tilt of the vehicle with respect to the horizontalplane, and, as a result, (ii) reduce unpleasant glare given to a driverof an oncoming vehicle etc. Further, a moving mechanism for changing theposition of the range of floodlighting a1 can be downsized as comparedwith the moving mechanism for moving a conventional reflector. Thismakes it possible to change the position of the range of floodlightinga1 in the vertical direction quickly. That is, the headlamp 100 can besuitably employed to reduce unpleasant glare or dazzle given to a driverof an oncoming vehicle etc.

Specifically, as shown in FIG. 14, the tilt detection section 15 detectstilt of a vehicle, and finds a tilt angle of the vehicle in ananterior-posterior direction (S11). Then, the tilt detection section 15supplies, to the emission control section 4, an angle signal indicatingthe tilt angle. In accordance with the angle signal, the emissioncontrol section 4 controls whether each of the plurality of laserelements 2 emits a laser beam or not. That is, the emission controlsection 4 controls, on the basis of the angle signal, whether each ofthe plurality of laser elements 2 emits a laser beam or not, so as tochange an area or a position of the irradiation region formed on thelight-emitting section 3 by the laser beam (S12).

For example, (a) of FIG. 15 illustrates a case where the vehicle 110 isdriven on a flat road. In this case, the emission control section 4drives all the plurality of laser elements 2, so as to irradiate theentire light-emitting section 3 with the laser beam. Here, the vehicleforms, for example, the range of floodlighting a1 in a range from anangle −α to an angle +α with respect to a front direction of theheadlamp 100. Note here that (a) of FIG. 15 illustrates a case whereeach of twelve laser elements 2 emits a laser beam to thelight-receiving surface of the light-emitting section 3 so that 4×3irradiation regions are formed on the light-receiving surface in amatrix manner.

As compared with (a) of FIG. 15, (b) of FIG. 15 illustrates a case wherethe vehicle starts going up the uphill slope which is tilted at an angleof θ1 with respect to the horizontal plane, for example. Here, theemission control section 4 controls, for example, whether each of theplurality of laser elements 2 emits a laser beam or not so that noirradiation region is formed on a vertically-upper stage C1 of thelight-emitting section 3. As a result, the headlamp 100 forms the rangeof floodlighting a1 in a range from an angle −α to an angle β(β<α) withrespect to the front direction of the headlamp 100.

Further, as illustrated in (c) of FIG. 15, in a case where the vehiclegoes up the uphill slope which is tilted at an angle of θ2 (>θ1) withrespect to the horizontal plane, the emission control section 4 controlswhether each of the plurality of laser elements 2 emits a laser beam ornot so that no irradiation region is formed on a vertically-upper stageC2 of the light-emitting section 3. As a result, the headlamp 100 formsthe range of floodlighting a1 in a range from an angle of −α to an angleof γ (γ<β) with respect to the front direction of the headlamp 100.

In this way, with the control carried out by the emission controlsection 4, the headlamp 100 can change, in accordance with the tilt ofthe road, the range of floodlighting a1 so as not to give an influenceon a driver of an oncoming vehicle etc. It is therefore possible toreduce unpleasant glare or dazzle given to a driver of an oncomingvehicle etc.

Further, in the above description, Operational Example 4 deals with acase where a vehicle goes up an uphill slope, as an example. Note,however, that in a case where the vehicle goes down a downhill slope,control similar to the control for the uphill slope can be carried out.With such control, it is possible to reduce unpleasant glare or dazzlegiven to a driver of an oncoming vehicle when the vehicle goes down adownhill slope.

Note that, the headlamp 100 can find out whether the vehicle goes up aslope or goes down a slope in such a manner that the objectidentification section 14 analyzes a moving image obtained with the useof the camera 16. In this case, the headlamp 100 does not necessarilyinclude the tilt detection section 15.

Modification examples of the headlamp 100, i.e., a headlamp 200, aheadlamp 300, a headlamp 400, and headlamp 500, are described below.

Modification Example 1

Next, the headlamp 200 (a light-emitting device, a vehicle headlight)which is a modification example of the headlamp 100 is described belowwith reference to FIG. 17. FIG. 17 is a schematic view illustrating anexample of the headlamp 200. Unlike the headlamp 100, the headlamp 200includes an elliptic mirror 20 (light-casting section) and a convex lens11, in place of a parabolic mirror 5 (see FIG. 17). The followingdescription deals with the elliptic mirror 20 and the convex lens 11which are included in the headlamp 200.

(Elliptic Mirror 20)

The elliptic mirror 20 controls light emitted from the light-emittingsection 3 by reflecting the light, in the same manner as the parabolicmirror 5. Further, the elliptic mirror 20 casts light toward a lightdistribution area (a light-castable range) which is a range in which theheadlamp 200 (which includes the elliptic mirror 20) is capable ofcasting light. That is, the range of floodlighting a1 (see FIG. 3) isformed by illumination light emitted from the light-emitting section 3in response to laser beams emitted from the plurality of laser elements2.

Further, the elliptic mirror 20 casts the illumination light emittedfrom the light-emitting section 3.

According to the present modification example, the elliptic mirror 20 isobtained by coating FRP serving as a substrate with (i) Al serving as areflective film and further with (ii) silicon oxide thereon, serving asan antioxidant for the Al coat.

Note, however, that the elliptic mirror 20 is not limited to thisstructure, as long as the elliptic mirror 20 has a function ofreflection control. For example, the substrate of the elliptic mirror 20can be made from another resin, such as acryl or polycarbonate, or canbe a metallic member made from, for example, Al. The reflective film ofthe elliptic mirror 20 can be made from Ag or Pt. Further, the oxidationresistant film of the elliptic mirror 20 can be made from aluminumoxide, or can be a film which (i) employs a silicon oxide film and atitanium oxide film as a multilayer film and (ii) has an enhancedreflection function.

The elliptic mirror 20 of the present embodiment has an arrangement inwhich (i) an inner surface of the elliptic mirror made from a resin iscoated with aluminum, (ii) an opening is of 38 mm in diameter, and (iii)a distance between a first focal point and a second focal point is 32.5mm.

At least a part of the reflecting surface of the elliptic mirror 20 hasan elliptical shape, and the elliptic mirror 20 has the first focalpoint on a laser beam incident side. Moreover, the elliptic mirror 20has the opening in a direction in which the light emitted from thelight-emitting section 3 is distributed, and has the second focal pointon an opening side.

Light emitted from the light-emitting section 3, which is positioned atsubstantially the first focal point of the elliptic mirror 20, isreflected by the elliptic mirror 20 to be converged in the vicinity ofthe second focal point.

(Convex Lens 11)

The convex lens 11 causes light, which has been emitted from thelight-emitting section 3 and has passed through a wavelength cut coating10, to be substantially collimated light. Then, the convex lens 11 caststhe substantially collimated light in front of the headlamp 200. Thismakes it possible to cast efficiently, within a solid angle, lightemitted from the light-emitting section 3, so as to form the range offloodlighting a1. As a result, it is possible to have an improvement inuse efficiency of the light.

Moreover, a position of the second focal point of the elliptic mirror 20and a position of a focal point of the convex lens 11 are substantiallyidentical with each other.

The convex lens 11 is supported by the wavelength cut coating 10 or theelliptic mirror 20 by being attached thereto. A surface of the convexlens 11, which surface is in contact with the wavelength cut coating 10or the elliptic mirror 20, is substantially identical in size with thewavelength cut coating 10 (that is, the opening of the elliptic mirror20). Further, a line, which passes through a principal point of theconvex lens 11 and is orthogonal to a main plane of the convex lens 11,extends on a plane which extends through the first focal point and thesecond focal point of the elliptic mirror 20.

Modification Example 2

Next, the headlamp 300 (a light-emitting device, a vehicle headlight),which is another modification example of the headlamp 100, is describedbelow with reference to FIG. 18. FIG. 18 is a schematic viewillustrating an example of the headlamp 300. Unlike the headlamp 100,the headlamp 300 includes collimating lenses 30 (optical controlsections) in place of initial mirrors 6 (see FIG. 18). The followingdescription deals with the collimating lenses 30 included in theheadlamp 300.

(Collimating Lens 30)

The collimating lenses 30 are provided between the plurality of laserelements 2 and the light-emitting section 3, and control guide of laserbeams emitted from the plurality of laser elements 2 toward thelight-emitting section 3. The collimating lenses 30 are arranged to facerespective light-emitting points of the plurality of laser elements 2,that is, the collimating lenses 30 and the plurality of laser elements 2correspond to each other, respectively. The laser beams transmitted bythe collimating lenses 30 pass through a window section of the ellipticmirror 20 and reach the light-emitting section 3.

Here, in a case where the initial mirrors 6 are used as the lightcontrol sections, a travelling direction of the laser beam toward theinitial mirrors 6 and a travelling direction of the laser beam which hasbeen reflected by the initial mirrors 6 are different from each other.That is, the initial mirror 6 can change the travelling direction of thelaser beam to be different from a direction of an optical axis of alight-emitting point of the laser element 2.

Accordingly, with the use of the initial mirrors 6, it is possible toarrange the plurality of laser elements 2 so that the light-emittingpoints of the plurality of laser elements 2 face in a direction (forexample, a vertically-upward direction) which is different from adirection toward the opening of the elliptic mirror 20, as illustratedin FIG. 17 for example. Accordingly, in the case of FIG. 17, (i) theheat radiating base 7 is provided so that a surface of the heatradiating base 7 faces in the vertically-upward direction and (ii) theplurality of laser elements 2 are provided on the surface of the heatradiating base 7.

On the other hand, unlike the arrangement employing the initial mirrors6, a direction of an optical axis of the light-emitting point of thelaser element 2 and a travelling direction of the laser beam which haspassed through the collimating lens 30 are substantially identical witheach other.

For this reason, with the use of the collimating lenses 30, it isnecessary to arrange the plurality of laser elements 2 so that adirection in which the light-emitting point of each of the plurality oflaser elements 2 faces is substantially identical with a directiontoward the opening of the elliptic mirror 20, as illustrated in FIG. 18for example. Accordingly, in the case of FIG. 18, (i) the heat radiatingbase 7 is provided so that a surface of the heat radiating base 7 facesin a direction which is substantially identical with the directiontoward the opening, and (ii) the plurality of laser elements 2 areprovided on the surface.

For this reason, in order to reduce thermal resistance of each of theplurality of laser elements 2 with respect to the heat radiating base 7,parts of the surface of the heat radiating base 7 which parts face theplurality of laser elements 2, respectively, are required to havedifferent angles with respect to the vertically-upward direction.Accordingly, from the viewpoint of versatility of the heat radiatingbase 7, the headlamp 200 employing the initial mirrors 6 is morepreferable than the headlamp 300 employing the collimating lenses 30,because, with the initial mirrors 6, it is unnecessary to treat thesurface of the heat radiating base 7 on which surface the plurality oflaser elements 2 are provided.

Examples of the method for reducing thermal resistance of each of theplurality of laser elements 2 with respect to the heat radiating base 7include (i) a method in which parts of the heat radiating base 7 arecaused to have different angles, respectively, in accordance withrespective optical paths of the plurality of laser elements 2, and (ii)a method in which the heat radiating base 7 is entirely curved.

Further, in the arrangement employing the collimating lenses 30 insteadof the initial mirrors 6, it is impossible to carry out beamcompression. For this reason, that arrangement requires a larger windowof the elliptic mirror 20 than the arrangement employing the initialmirrors 6. Accordingly, from the viewpoint of floodlighting efficiencyof the elliptic mirror 20, the headlamp 200 is more preferable than theheadlamp 300.

The collimating lenses 30 can be convex lenses.

Modification Example 3

Next, the headlamp 400 (a light-emitting device, a vehicle headlight),which is another modification example of the headlamp 100, is describedbelow with reference to FIGS. 19 through 21. FIG. 19 is a schematic viewillustrating an example of the headlamp 400. FIG. 20 is a schematic viewillustrating examples of a configuration in the vicinity of a laserelement array 40. FIG. 21 is a view illustrating other examples of theconfiguration in the vicinity of the laser element array 40. Unlike theheadlamp 100, the headlamp 400 includes (i) the laser element array 40in which the plurality of laser elements 2 are arranged in an array,(ii) an initial mirror 44 (light control sections, mirrors) in which aplurality of initial mirrors 6 are arranged in an array, (iii) a stem 43(a seat, a housing), and (iv) a cap 45 (a housing) (see FIG. 19).

Note that the laser element array 40 has a basic structure which is alaser beam source group including a plurality of laser beam sources,each of which is made up of a laser chip 41 and a sub-mount 42.

Further, the stem 43 and the cap 45 constitute a single housing in whichthe laser element array 40 and the initial mirror 44 are provided. Thisstructure allows reducing thermal resistance between the laser chip 41and the stem 43.

Accordingly, in a case where the same heat radiating base 7 and the samefin 8 as those of the headlamp 100 are employed in the headlamp 400, itis possible for the headlamp 400 to have an increase in systemreliability, as compared with the headlamp 100. From another point ofview, in a case where the same system reliability as that of theheadlamp 100 is set to the headlamp 400, it is possible to downsize theheadlamp 400 entirely, as compared with the headlamp 100. That is, it ispossible to have a reduction in size of the light-emitting device 1(headlamp 400).

Moreover, it is easy to control positioning of the laser chips 41 andthe initial mirror 44 relative to each other. This allows an increase inproduction yield of the headlamp 400.

Further, with the headlamp 400, it is possible to downsize the window ofthe elliptic mirror 20, as compared with the headlamp 300.

(Laser Element Array 40)

The laser element array 40 is in contact with a single stem 43 attachedto the heat radiating base 7, and is made up of a plurality of laserchips 41 and a plurality of sub-mounts 42. As illustrated in (c) of FIG.20, the plurality of laser chips 41 are arranged on the plurality ofsub-mounts 42, respectively.

Each of the plurality of laser chips 41 has a function similar to thatof a chip included in each of the plurality of laser elements 2. Each ofthe plurality of sub-mounts 42 serves as a die-bonding section for acorresponding one of the plurality of laser chips 41. For example, asillustrated in (a) and (b) of FIG. 20, the plurality of laser chips 41and the plurality of sub-mounts 42 are arrayed so as to form the laserelement array 40. That is, by employing such a laser element array 40 asa laser beam source group, it becomes possible to downsize thelight-emitting device 1. Details of arrangements illustrated in (a) and(b) of FIG. 20 are described below more specifically.

(Stem 43)

The stem 43, which is thermally conductive, has (i) a surface (a secondplane, an outer part of the stem 43, having a largest area) which facesthe heat radiating base 7 and (ii) a surface (a first plane, a surfacemost of which is sealed with the cap 45) which is substantially parallelto the second plane (see FIG. 20).

The laser element array 40 and the initial mirror 44 are in contact withthe first plane of the stem 43. With the arrangement, heat generated bythe laser element array 40 is directly guided from the first plane tothe second plane, so that the heat is not retained in the stem 43 butguided to the fins 8 via the heat radiating base 7. Consequently, it ispossible to cool the laser element array 40 efficiently. Further, sincethe laser element array 40 is in contact with the first plane, it ispossible to downsize the light-emitting device 1 as compared with a casewhere the laser element array 40 is provided in a position other than aposition on the first plane of the stem 43.

In the above description, the present modification example deals with acase where the stem 43 and the light-emitting section 3 are arranged sothat the center of the first plane of the stem 43 substantially facesthe light-emitting section 3, as illustrated in FIG. 19. Note, however,that it is possible to arrange, like the headlamp 100, the heatradiating base 7 in a lateral direction in FIG. 19 (so that the surfaceof the heat radiating base 7 faces in the vertically-upward direction)by providing a mirror between the light-emitting section 3 and the laserelement array 40. In this case, it is possible to cause the stem 43 anda light-emitting section supporter 9 to share the heat radiating base 7.

(Initial Mirror 44)

The initial mirror 44 has the same function as that of the initialmirror 6, and is provided to face the laser element array 40. Theinitial mirror 44 is provided at substantially the center of the firstplane of the stem 43. With the arrangement, a laser beam emitted fromeach of the plurality of laser chips 41 of the laser element array 40reaches the initial mirror 44 appropriately, so that the initial mirror44 guides the laser beam toward the light-emitting section 3 byreflecting the laser beam. Further, with the arrangement, it is possibleto efficiently radiate heat generated due to reflection loss of thelaser beam at the initial mirror 44, which reflection loss is caused insuch a manner that the initial mirror 44 does not reflect the laser beambut absorbs the laser beam, for example.

Further, it is preferable that the initial mirror 44 is attached to thefirst plane of the stem 43 and then the plurality of laser chips 41 areattached to the plurality of sub-mounts 42, respectively. In this case,it is possible to adjust easily an installation position of the laserelement array 40 in consideration of (i) control of guide of the laserbeam, (ii) a light-emitting shape of the light-emitting section 3, (iii)a position of a light-emitting point of the light-emitting section 3etc. It becomes therefore possible to manufacture the light-emittingdevice 1 more easily.

Furthermore, it is possible to employ either an arrangement in which one(1) initial mirror 44 is provided to face one (1) laser element array40, or another arrangement in which a plurality of initial mirrors 44are provided to face the plurality of laser chips 41 of the laserelement array 40, respectively.

In a case where the initial mirror 44 is constituted by a plurality ofinitial mirrors, the initial mirror 44 preferably is an array mirror.Such an array mirror is obtained by forming, in accordance with thelight-emitting shape of the light-emitting section 3, plural kinds ofinitial mirrors with differently curved reflective surfaces at once. Forthis reason, with the use of such an array mirror, it is possible tosimplify a manufacturing process. Further, since the initial mirror 44being an array mirror is provided for each of the plurality of laserchips 41, it is possible to guide the laser beam emitted from each ofthe plurality of laser chips 41 to the light-emitting section 3accurately.

(Cap 45)

The cap 45 seals the first plane of the stem 43 so as to protect thelaser element array 40 and the initial mirror 44, as illustrated in FIG.20. An inner space sealed with the cap 45 is filled with dry air. Asealing method may be a resistance welding method, but other methods canbe also used for the sealing.

With the cap 45, it is possible to prevent the laser beam fromcollecting dust, and also prevent dust or dirt from falling on the laserelement array 40 and the initial mirror 44. A part (at least a part onthe optical path formed by the laser beam) of the cap 45 is made of atransparent plate (e.g., kovar glass), and transmits the laser beamwhich has been reflected by the initial mirror 44.

(Variation of Laser Element Array 40)

Next, a variation of the laser element array 40 is described below withreference to (a) and (b) of FIG. 20. Note that, each of laser elementarrays 40 a and 40 b has the same function as that of the laser elementarray 40, and each of initial mirrors 44 a and 44 b has the samefunction as that of the initial mirror 44. Each of sub-mount groups 42 aand 42 b is constituted by a plurality of sub-mounts 42.

In the case of (a) of FIG. 20, two initial mirrors 44 a are provided atsubstantially the center of the stem 43, and two laser element arrays 40a (a first laser beam source group and a second laser beam source group)are provided to face the respective two initial mirrors 44 a.

Each of the laser element arrays 40 a and each of the sub-mount groups42 a have a rectangular shape as viewed from the first plane of the stem43. In this case, even if a plurality of laser beam sources, each beingconstituted by a laser chip 41 and a sub-mount 42, are provided, theplurality of laser beam sources can be provided in block as a laser beamsource group, that is, it is possible to have a reduction in area of aregion where the plurality of laser beam sources are provided. Further,each of the two initial mirrors 44 a is an array mirror.

(a) of FIG. 20 deals with a case where two laser element arrays 40 a areprovided. Note, however, that the present embodiment is not limited tothis, and it is possible to provide three or more laser element arrays40 a. For example, it is possible to divide one of the two laser elementarrays 40 a illustrated in (a) of FIG. 20 into two laser element arrays.

Further, in the case of (b) of FIG. 20, a single laser element array 40b is provided to face an initial mirror 44 b which is provided atsubstantially the center of the stem 43. The laser element array 40 band a sub-mount group 42 b each have a circular shape as viewed from thefirst plane of the stem 43. That is, the laser element array 40 b isprovided to surround the initial mirror 44 b. In this case, it ispossible to have a reduction in size of the light-emitting device 1 ascompared with a case where the laser element array 40 b is formed tohave a rectangular shape (as illustrated in (a) of FIG. 20).

Other variations of the laser element array 40 are described below withreference to FIG. 21. Each of arrangements illustrated in (a) and (b) ofFIG. 21 is different from the arrangements illustrated in (a) and (b) ofFIG. 20 in that there is provided a stem 243 having a convex section 243a and the convex section 243 a is provided with the laser element arrays40 a. That is, in each of the arrangements illustrated in (a) and (b) ofFIG. 21, the laser element arrays 40 a are provided not on the firstplane of the stem 43 but on a side surface of the convex section 243 a(a plane perpendicular to the first plane and the second plane) so thatthe light-emitting point of the laser chip 41 faces toward thelight-emitting section 3.

In this case, the heat generated by the laser element arrays 40 a isretained at the convex section 243 a, as compared with the arrangementsillustrated in (a) and (b) of FIG. 20. Accordingly, in consideration ofheat radiating efficiency, the arrangements illustrated in (a) and (b)of FIG. 20 are more preferable than the arrangements illustrated in (a)and (b) of FIG. 21.

Further, the arrangement illustrated in (b) of FIG. 21 is different fromthe arrangement illustrated in (a) of FIG. 21 in that a cap 245including collimating lenses 30 is provided so that the collimatinglenses 30 face the laser element arrays 40 a, respectively. With thearrangement illustrated in (b) of FIG. 21, it is unnecessary to providethe collimating lenses separately 30. Accordingly, with the arrangementillustrated in (b) of FIG. 21, it is possible to have a reduction insize of the light-emitting device 1, as compared with the arrangementillustrated in (a) of FIG. 21.

Note, however, that, with the arrangements illustrated in (a) and (b) ofFIG. 21, it is necessary to have a reduction in size of the convexsection 243 a so as to have a reduction in distance between beams (adistance between the laser element arrays 40 a). This increases thethermal resistance of the laser element arrays 40 a with respect to theheat radiating base 7. That is, a reduction in distance between thebeams and a reduction in thermal resistance conflicts each other. Forthis reason, it is preferable to employ the arrangements illustrated in(a) and (b) of FIG. 20.

Modification Example 4

Next, the headlamp 500 (a light-emitting device, a vehicle headlight),which is another modification example of the headlamp 100, is describedbelow with reference to FIG. 22. FIG. 22 is a schematic viewillustrating an example of the headlamp 500. Unlike the headlamp 100,the headlamp 500 includes a bundle fiber 50 (a light control section, alight guide section, an optical fiber) in place of the initial mirror 6(see FIG. 22).

(Bundle Fiber 50)

The bundle fiber 50 is a bundle of a plurality of optical fibers. Thebundle fiber 50 controls the laser beam emitted from each of theplurality of laser elements 2 to travel toward the light-emittingsection 3. The bundle fiber 50 includes incident end sections 50 a forreceiving laser beams emitted from the plurality of laser elements 2,and emission end sections 50 b for emitting the laser beams to thelight-emitting section 3. With the use of the bundle fiber 50, it isnecessary to only provide the plurality of laser elements 2 on anincident end section 50 a side. Accordingly, it is possible to arrangethe plurality of laser elements 2 in consideration of convenience incontrolling or replacing the plurality of laser elements 2. Such anarrangement can be realized since the bundle fiber 50 has flexibility.

The incident end sections 50 a of the bundle fiber 50 are connected tothe plurality of laser elements 2 via butt joints (not illustrated).

Further, the emission end sections 50 b are located in the vicinity ofthe window of the elliptic mirror 20, and emit the laser beams towardthe light-emitting section 3 from outside the elliptic mirror 20. Inthis case, it is possible to have an increase in reflection efficiencyof the light emitted from the light-emitting section 3. Note that, thepresent embodiment is not limited to this, and the emission end sections50 b can be provided inside the elliptic mirror 20. In this case, it ispossible to have an increase in accuracy in irradiating thelight-emitting section 3 with the laser beams.

Moreover, the emission end sections 50 b of the bundle fiber 50 arepreferably arranged so as to be capable of forming the irradiationregions illustrated in FIG. 6 (a). In this case, it is preferable toarrange the emission end sections 50 b in accordance with theaforementioned arrangement of the plurality of laser elements 2. Thatis, at least two of the plurality of emission end sections 50 b areprovided so that, among the irradiation regions formed on thelight-emitting section 3 by the laser beams emitted from the respectiveplurality of laser elements 2, irradiation regions corresponding to theat least two of the emission end sections 5 are provided in differentpositions, respectively. In other words, the plurality of laser elements2 emit laser beams so that, among the irradiation regions formed on thelight-emitting section 3 by the laser beams emitted from the respectiveplurality of laser elements 2, at least two of the irradiation regionsare formed in different positions, respectively.

Further, according to the present modification example, the incident endsection 50 a and the emission end section 50 b of the bundle fiber 50each have a numerical aperture (NA) of 0.18.

Note, however, that it is possible to adjust an NA of the light-emittingsection 3 and an NA of the incident end section 50 a, so as to have areduction in excitation area of the light source section (laser element2) while maintaining coupling efficiency of the laser beam. In thiscase, the adjustment is carried out so that the NA of the light-emittingsection 3 is greater than the NA of the incident end section 50 a.

The plurality of laser elements 2 and the bundle fiber 50 are notnecessarily connected to each other via the butt joints, and can beoptically connected to each other by use of lenses or mirrors. Further,the light-emitting section 3 and the bundle fiber 50 may be opticallyconnected to each other by providing lenses or mirrors therebetween.

Further, it is preferable that a core of each of the plurality ofoptical fibers constituting the bundle fiber 50 has a polygonal crosssection taken in a direction perpendicular to a direction in which thelaser beam is guided. In this case, it is possible to arrange theplurality of optical fibers more densely as compared with a case wherethe core has a circular cross section. Accordingly, with such anarrangement, it becomes easy to irradiate a desired position on thelight-emitting section 3 with a laser beam emitted from each of theplurality of laser elements 2.

The bundle fiber 50 of the present variation is constituted by a bundleof multimode fibers. Energy intensity distribution (light intensitydistribution) of the laser beam emitted from each of the plurality oflaser elements 2 is substantially identical with Gaussian distribution.However, with the use of the multimode fibers, it is possible to convertthe energy intensity distribution of the laser beam into substantiallytop hat distribution (in which the energy intensity distribution issubstantially uniform). Accordingly, it becomes possible to suppressdeterioration of the light-emitting section 3 due to irradiation withthe laser beam.

[Other Arrangements]

The light-emitting section 3 of each of the headlamps 100 through 500described above is such that, on receipt of the laser beam emitted fromeach of the plurality of laser elements 2, the light-emitting section 3emits fluorescence mainly toward a laser element 2 side. Such alight-emitting section is called “reflective light-emitting section” inthe present specification.

The light-emitting section 3 of the present embodiment is notnecessarily the “reflective light-emitting section”. For example, it ispossible to employ a light-emitting section in which (i) alight-receiving surface of the light-emitting section is irradiated witha laser beam emitted from each of the plurality of laser elements 2, and(ii) the light-emitting section emits fluorescence mainly toward a sideopposite to the light-receiving surface. Such a light-emitting sectionis called “transmissive light-emitting section” in the presentspecification.

In an arrangement employing the “transmissive light-emitting section”,the light-emitting section is provided on the light-emitting sectionsupporter 9, for example, and a laser beam incident to thelight-emitting section is converted into fluorescence, and then, thefluorescence is emitted mainly toward a side opposite to the laserelement 2 side.

Various embodiments of the light-emitting device of the presentembodiment and various embodiments of the vehicle headlight of thepresent embodiment are thus described. These various embodiments merelyindicate examples, and the embodiments explained here can be combinedwith each other appropriately, as a matter of course.

[Difference from Conventional Arts]

Finally, a light-emitting device in accordance with the presentembodiment including the foregoing various features can solve thefollowing problems of the techniques of Patent Literature 1 etc.

The vehicle headlamp of Patent Literature 1 emits a laser beam directlyto the outside, and includes no light-emitting section that emits lightin response to the laser beam. Therefore, the vehicle headlamp of PatentLiterature 1 has a problem of having an extremely low color renderingproperty of light having a wavelength other than a wavelength of thelaser beam.

As in the case of the vehicle headlamp of Patent Literature 1, theheadlight of Patent Literature 2 also includes no light-emitting sectionthat emits light in response to the laser beam. Therefore, the headlightof Patent Literature 2 has a problem of having an extremely low colorrendering property of light having a wavelength other than a wavelengthof the laser beam.

The vehicle lamp of Patent Literature 3 uses an LED as a light source.Since an LED is lower in luminance than a laser beam source, it isnecessary to increase a light-emitting area so as to obtain a necessaryluminous flux. Accordingly, in a case where an LED light source is usedin an automobile or a motorcycle which is limited in size of a lamp,there occurs a problem such that the LED light source irradiates a widerregion than a laser beam source and it is therefore impossible to reducea size of a lamp such as a running light that is required to cast lightat a narrow angle.

Further, according to the vehicle lamp of Patent Literature 3, it isdifficult in terms of a vehicle front space to set a lamp which isfurther required to cast light at a narrow angle than a running light,e.g., which illuminates only an object (e.g., a human) existing at aplace to be irradiated (e.g., 40 meters ahead) or does not illuminateonly an object (e.g., an opposite lane). It is also difficult to freelychange a light distribution pattern by combining a plurality ofnarrow-angle light-casting devices.

In addition, according to the vehicle lamp of Patent Literature 3, thereexists a non-light-emitting part between respective LEDs. Therefore, thevehicle lamp needs to be used while being blurred at an irradiatedposition. This makes it impossible to obtain a contrast (which clarifiesa boundary between a bright part and a dark part). Note that, in a casewhere the vehicle lamp is used without being blurred at an irradiatedposition, a higher contrast is obtained but a non-light-emitting partbetween respective LEDs is projected. Therefore, for example, in a casewhere two LEDs turn on, bright-dark-bright floodlighting occurs.

The light source device of Patent Literature 4 is a device which merelyemits light, i.e., a device which merely illuminates. Patent Literature4 discloses, as light control means for changing an emission rangeand/or an intensity distribution of excitation light, a method formoving a solid light source and a method for moving a mirror.

However, in a case where the light source device of Patent Literature 4uses a solid light source, even if the light source device uses asemiconductor laser having high directivity, a beam diffusion angle isas wide as 40°. Therefore, though it is possible to change an emissionrange and/or an intensity distribution of excitation light, it isimpossible to excite only any place in a fluorescent body layer.

Further, the light source device of Patent Literature 4 is not arrangedto control an irradiated position and an irradiation region (a spotsize) in a fluorescent body part for each of beams of light emitted froma plurality of solid light sources. Accordingly, the light source deviceof Patent Literature 4 is incapable of uniformly irradiating an entiresurface of a fluorescent body layer (cause the entire surface of thefluorescent body layer to uniformly emit light). In addition, for asimilar reason, the light source device of Patent Literature 4 has aproblem of being incapable of exciting the fluorescent body layer in acomplicated shape (e.g., preventing a central part of the fluorescentbody layer from emitting light and causing a circumference of thefluorescent body layer to emit light).

Patent Literature 4 also discloses (i) an arrangement in whichfluorescence is cast by providing a fluorescent body layer at a focalpoint of a lens system and (ii) an arrangement in which a light-emittingcomponent that is emitted in a front direction is increased by providinga reflection layer on a side surface of the fluorescent body layer.However, the light source device of Patent Literature 4 exhibits acharacteristic of substantially Lambertian-shaped distribution offluorescence. This prevents all fluorescence from entering an apertureof a lens, so that the light source device becomes an optical systemwhich is extremely great in loss.

Moreover, according to the light source device of Patent Literature 4,it is necessary to increase NA (numerical aperture) (which is determineddepending on a lens aperture and a lens focal distance) so as to usefluorescence with higher efficiency. However, according to the lightsource device of Patent Literature 4, a fluorescent body is excited bycausing excitation light to pass between the fluorescent body layer anda lens. Therefore, in a case where a lens having large NA is used,excitation light is rejected by the lens since the excitation light isdispersed at a large angle. This prevents effective excitation of thefluorescent body layer. Contrary to this, it is necessary to reduce NAso that excitation light is effectively emitted. This prevents effectivecasting of fluorescence. Namely, the light source device of PatentLiterature 4 is a system which is extremely low in efficiency.

Furthermore, according to the light source device of Patent Literature4, in order to move the solid light source and to make the light sourcedevice to be smaller and lower in weight, the solid light source is notcooled while the fluorescent body layer is cooled. This makes itimpossible to obtain a luminance necessary for narrow-anglefloodlighting by a vehicle lamp.

Further, Patent Literature 4 discloses a method which uses a digitalmicromirror device (DMD). This method is excellent in that an excitationrange of the fluorescent body layer is controlled (patterned). However,according to the method, the digital micromirror device is entirelyilluminated, and only light emitted to a part of the digital micromirrordevice is used. This causes a problem such that energy as much as unusedlight is lost and thus the light source device of Patent Literature 4 islow in efficiency, i.e., consumes more electric power.

In addition, the light source device of Patent Literature 4 usesexcitation light having a light intensity distribution such that anemission range and/or an intensity distribution of the excitation lightis changed by moving an exciting light source. This causes a problemsuch that the DMD surface also has a light intensity distribution and itis therefore impossible to obtain a sufficient contrast at a place witha weak light intensity even by turning on/off a micromirror.

A light-emitting device and the like in accordance with the presentembodiment have been made in view of the above problems, and alight-emitting device and a vehicle headlight each having a high colorrendering property and being capable of realizing any light distributionpattern are provided.

[Summary]

A light-emitting device in accordance with one aspect of the presentinvention is a light-emitting device, including: a plurality of laserbeam sources each for emitting a laser beam; a light-emitting sectionfor emitting light in response to the laser beam emitted from at leastone of the plurality of laser beam sources; and emission control meansfor controlling whether each of the plurality of laser beam sourcesemits light or not, at least a part of the plurality of laser beamsources being positioned in such a manner that irradiation regions ofthe light-emitting section which are respectively irradiated with thelaser beams emitted from the plurality of laser beam sources arepositioned at least partially differently.

With the arrangement, the plurality of laser beam sources are positionedin such a manner that the irradiation regions of the light-emittingsection are positioned at least partially differently, and each of theplurality of laser beam sources is controlled whether to emit light ornot, so that a light distribution pattern of illumination light can bechanged freely.

In this case, a light-emitting device in accordance with one aspect ofthe present invention secures sufficient luminance by using laser beamsources. Furthermore, inclusion of the light-emitting section foremitting light in response to the laser beam enables the light-emittingdevice to have improved color rendering property and higher contrast oflight whose wavelength is other than that of the laser beam.

That is, the light-emitting device in accordance with one aspect of thepresent invention has color rendering property that enables thelight-emitting device to be used for a vehicle headlamp, and is capableof changing a light distribution pattern.

Furthermore, it is preferable to arrange the light-emitting device inaccordance with one aspect of the present invention to further includeat least one light control section for controlling guide of the laserbeams emitted from the plurality of laser beam sources toward thelight-emitting section.

With the arrangement, said at least light control section controls guideof the laser beams, so that the plurality of laser beam sources can bepositioned freely with respect to the light-emitting section.

Furthermore, it is preferable to arrange the light-emitting device inaccordance with one aspect of the present invention such that said atleast one light control section is a mirror for controlling guide of thelaser beams emitted from the plurality of laser beam sources byreflecting the laser beams emitted from the plurality of laser beamsources.

With the arrangement, said at least one light control section is amirror, which allows reducing deterioration in a coat film compared to acase where all light control sections are lenses. This allows improvingdurability of the light control section.

Furthermore, it is preferable to arrange the light-emitting device inaccordance with one aspect of the present invention such that said atleast one light control section includes an enhanced reflectionstructure.

With the arrangement, said at least one light control section includesan enhanced reflection structure, which enables said at least one lightcontrol section to reduce loss of reflection of the laser beam. That is,it is possible to reduce mirror loss of said at least one light controlsection.

Furthermore, it is preferable to arrange the light-emitting device inaccordance with one aspect of the present invention such that theplurality of laser beam sources and said at least one light controlsection are included in a single housing.

With the arrangement, the plurality of laser beam sources and said atleast one light control section are included in a single housing, whichenables the light-emitting device to be smaller in size. Furthermore,since the plurality of laser beam sources are included in a singlehousing, it is possible to prevent the laser beams (e.g. ultraviolet)emitted from the laser beam sources from collecting dusts.

Furthermore, it is preferable to arrange the light-emitting device inaccordance with one aspect of the present invention such that theplurality of laser beam sources constitute at least a first laser beamsource group and a second laser beam source group, and said at least onelight control section includes a plurality of light control sectionscorresponding to the first laser beam source group and the second laserbeam source group, respectively.

With arrangement, the plurality of laser beam sources constitute atleast a first laser beam source group and a second laser beam sourcegroup, which enables the light-emitting device to have smaller regionswhere the laser beam sources are provided. This enables thelight-emitting device to be smaller in size. Furthermore, since theplurality of light control sections are positioned in such a manner asto correspond to the first laser beam source group and the second laserbeam source group, respectively, it is possible to suitably and easilyradiate the light-emitting section with the laser beams emitted from thelaser beam sources while downsizing the light-emitting device.

Furthermore, it is preferable to arrange the light-emitting device inaccordance with one aspect of the present invention such that theplurality of laser beam sources are positioned around said at least onelight control section.

With the arrangement, it is possible to downsize the light-emittingdevice compared to a case where a plurality of laser beam sources arepositioned to be in line for example.

Furthermore it is preferable to arrange the light-emitting device inaccordance with one aspect of the present invention such that said atleast one light control section includes a plurality of light controlsections, the plurality of light control sections constitute at leastone array mirror, and the plurality of laser beam sources are positionedin such a manner as to face the plurality of light control sections,respectively.

With the arrangement, the plurality of light control sections are arraymirrors. In this case, plural kinds of mirrors with different reflectioncurves can be made at once, which simplifies a production process.Furthermore since the laser beam sources are positioned in such a manneras to correspond to the light control sections, respectively, it ispossible to accurately guide the laser beams emitted from the laser beamsources to the light-emitting section.

Furthermore, it is preferable to arrange the light-emitting device inaccordance with one aspect of the present invention so as to furtherinclude: a seat which is thermally conductive; and a heat radiatingsection for radiating heat generated in the plurality of laser beamsources, the seat having a first plane to which the plurality of laserbeam sources are attached and a second plane to which the heat radiatingsection is attached, the first plane being substantially parallel to thesecond plane.

For example, in a case where a seat has a convex section on a firstplane and laser beam sources are attached to the convex section (i.e.the laser beam sources are attached to a portion other than the firstplane), heat generated from the laser beam sources remain in the seat,making it impossible to efficiently cool down the laser beam sources.

With the arrangement, the laser beam sources and the heat radiatingsection are attached to the first plane and the second plane of thethermally conductive seat, respectively. This enables the heat generatedfrom the laser beam sources to be directly transmitted from the firstplane of the seat to the second plane thereof, so that the heat istransmitted to the heat radiating section without remaining in the seat.This allows efficiently cooling down the laser beam sources.

Furthermore, since the laser beam sources are attached to the firstplane, it is possible to downsize the light-emitting device compared toa case where the laser beam sources are attached to a portion other thanthe first plane.

Furthermore, it is preferable to arrange the light-emitting device inaccordance with one aspect of the present invention such that said atleast one light control section is attached to the first plane of theseat.

With the arrangement, said at least one light control section isattached to the seat, so that heat generated due to loss of reflectionof the laser beam by the light control section, such as absorption ofthe laser beam by the light control section without reflecting the laserbeam, can be efficiently radiated.

Furthermore, in general, in a case where a laser beam source and a lightcontrol section are attached to the same object, the laser beam sourceis attached to the object after the light control section is attached tothe object. This allows easily adjusting where the laser beam source ispositioned in consideration of controlling guide of a laser beam andwhat shape the light-emitting section emits light in and wherelight-emitting points are positioned. This allows easy production of thelight-emitting device. With the arrangement, since the laser beamsources and the light control section are attached to the first plane ofthe seat, it is possible to easily adjust where the laser beam source ispositioned and to easily produce the light-emitting device.

Furthermore, it is preferable to arrange the light-emitting device inaccordance with one aspect of the present invention such that said atleast one light control section is at least one light guide sectionincluding an incident end section for receiving the laser beams emittedfrom the plurality of laser beam sources and an emission end section foremitting the laser beams to the light-emitting section.

With the arrangement, the light guide section receives a laser beam viathe incident end section and emits the laser beam via the emission endsection so as to guide the laser beam to the light-emitting section.This enables the laser beam sources to be provided closer to theincident end section. This enables the laser beam sources to bepositioned in consideration of control of the laser beam sources,easiness in replacement of the laser beam sources etc.

Furthermore, it is preferable to arrange the light-emitting device inaccordance with one aspect of the present invention such that said atleast one light guide section includes a plurality of light guidesections, and the plurality of light guide sections each include a corehaving a polygonal cross section taken in a direction perpendicular to adirection in which the laser beams are guided.

With the arrangement, it is possible to position the plurality of lightguide sections to be closer to each other compared to a case where thecore has a round cross section. This allows easily emitting the laserbeams to desired positions of the light-emitting section, respectively.

Furthermore, it is preferable to arrange the light-emitting device inaccordance with one aspect of the present invention such that said atleast one light guide section is a multimode fiber.

With the arrangement, since said at least one light guide section is amultimode fiber, it is possible to convert energy intensity distributionof the laser beam emitted from each of the laser beam sources, whichdistribution is substantially Gaussian distribution, into substantiallytop hat distribution. This enables the energy intensity distribution ofeach laser beam on the light-emitting section to be substantiallyconstant, thereby preventing deterioration in the light-emittingsection.

Furthermore, it is preferable to arrange the light-emitting device inaccordance with one aspect of the present invention so as to furtherinclude detection means for detecting an object in a light-castablerange which is a range in which the light-emitting device is capable ofcasting light, the emission control means controlling whether each ofthe plurality of laser beam sources emits light or not in accordancewith a result of detection by the detection means.

With the arrangement, the emission control means controls whether thelaser beam is emitted or not in accordance with the result of detectionby the detection means, so that light is cast to the detected object.This allows controlling a light distribution pattern of light to be castto the object. Consequently, it is possible to control the lightdistribution pattern in such a manner that, for example, the detectedobject is wholly or partially irradiated with light.

Furthermore, it is preferable to arrange the light-emitting device inaccordance with one aspect of the present invention so as to furtherinclude identification means for identifying the kind of the objectdetected by the detection means, and the emission control means controlswhether each of the plurality of laser beam sources emits light or notin accordance with the kind of the object identified by theidentification means.

With the arrangement, the light-emitting device further includes theidentification means for identifying, by image recognition, the kind ofthe object detected by the detection means. Therefore, by the emissioncontrol means controlling whether a laser beam is emitted or not inaccordance with the kind of the object identified by the identificationmeans, it is possible to control a light distribution pattern of lightcast to the object. Consequently, it is possible to control the lightdistribution pattern in such a manner that, for example, the detectedobject is wholly or partially irradiated with light or the detectedobject is not irradiated with light.

Furthermore, it is preferable to arrange the light-emitting device inaccordance with one aspect of the present invention so as to furtherinclude a light-casting section for casting the light emitted from thelight-emitting section, the light-emitting section being smaller in sizethan the light-casting section.

With the arrangement, the light-emitting section is smaller in size thanthe light-casting section, so that light emitted from the light-emittingsection can be efficiently cast in front of the light-casting section.

Furthermore, it is preferable that a vehicle headlamp in accordance withone aspect of the present invention includes the aforementionedlight-emitting device.

With the arrangement, the vehicle headlamp in accordance with one aspectof the present invention can cast light to anywhere, so that a lightdistribution pattern can be changed freely.

The present invention is not limited to the description of theembodiments above, but may be altered by a skilled person within thescope of the claims. An embodiment based on a proper combination oftechnical means disclosed in different embodiments is encompassed in thetechnical scope of the present invention.

INDUSTRIAL APPLICABILITY

The present invention relates to a light-emitting device which has highcolor rendering property and is capable of realizing any lightdistribution pattern. The present invention is applicable to a headlampfor a vehicle etc. in particular.

REFERENCE SIGNS LIST

-   1 Light-emitting device-   2 Laser element-   3 Light-emitting section-   4 Emission control section (emission control means)-   5 Parabolic mirror (light-casting section)-   6 Initial mirror (light control section, mirror)-   7 Heat radiating base (heat radiating section)-   8 Fin (heat radiating section)-   13 Object detection section (detection means)-   14 Object identification section (identification means)-   20 Elliptic mirror (light-casting section)-   30 Collimating lens (light control section)-   40 a, 40 b Laser element array (first laser beam source group,    second laser beam source group)-   41 Laser chip (laser beam source)-   42 Sub-mount (laser beam source)-   43 Stem (seat, housing)-   44, 44 a, 44 b Initial mirror (light control section, mirror, array    mirror)-   45 Cap (housing)-   50 Bundle fiber (light control section, light guide section, optical    fiber)-   50 a Incident end section-   50 b Emission end section-   100, 200, 300, 400, 500 Headlamp (light-emitting device, vehicle    headlight)-   243 Stem (seat, housing)-   245 Cap (housing)-   a1 Range of floodlighting-   a3 Range of floodlighting-   a4 Range of floodlighting

The invention claimed is:
 1. A light-emitting device, comprising: aplurality of laser beam sources each for emitting a laser beam; aflorescent unit for emitting light in response to the laser beam emittedfrom at least one of the plurality of laser beam sources; an emissioncontroller for controlling whether each of the plurality of laser beamsources emits light or not so as to adjust a pattern of the lightemitted from the florescent unit, at least a part of the plurality oflaser beam sources being positioned in such a manner that irradiationregions of the florescent unit which are respectively irradiated withthe laser beams emitted from the plurality of laser beam sources arepositioned at least partially differently, and at least one opticalelement for controlling guide of the laser beams emitted from theplurality of laser beam sources toward the florescent unit, wherein saidat least one optical element is at least one light guide including anincident end section for receiving the laser beams emitted from theplurality of laser beam sources and an emission end section for emittingthe laser beams to the florescent unit.
 2. The light-emitting device asset forth in claim 1, wherein said at least one light guide is amultimode fiber.
 3. The light-emitting device as set forth in claim 1,further comprising a computing unit for detecting an object in alight-castable range which is a range in which the light-emitting deviceis capable of casting light, the emission controller controlling whethereach of the plurality of laser beam sources emits light or not inaccordance with a result of detection by the computing unit.
 4. Thelight-emitting device as set forth in claim 3, wherein the computingunit identifies the kind of the object detected by the computing unit,and the emission controller controls whether each of the plurality oflaser beam sources emits light or not in accordance with the kind of theobject identified by the computing unit.
 5. The light-emitting device asset forth in claim 1, further comprising a light projection opticalmember for casting the light emitted from the florescent unit, theflorescent unit being smaller in size than the light projection opticalmember.
 6. A vehicle headlamp, comprising a light-emitting device as setforth in claim 1.